Test Suite and Sample Inputs¶
PSI4 is distributed with an extensive test suite, which can
be found in psi4/tests. After building the source code, these
can automatically be run by running ctest
in the compilation
directory. More info on ctest
options can be found
here. Sample input files
can be found in the psi4/samples subdirectory of the toplevel Psi
directory. The samples and a brief description are provided below.
Sample inputs accessible through interfaced executables are bulleted below.
Sample inputs for PSI4 as distributed are below.
Input File 
Description 

run some BLAS benchmarks 

TDHF test variable access 

CC2(RHF)/ccpVDZ energy of H2O. 

Gradient regularized asymptotic correction (GRAC) test. 

DFOMP2.5 ccpVDZ gradients for the H2O+ cation. 

DFMP2 ccpVDZ gradient for the NO molecule. 

incremental Cholesky filtered SCF 

metaGGA gradients of water and ssh molecules reference gradients updated due to new BraggSlater radii 

FSAPT0/junccpvdz procedure for methane dimer 

SAPT0 augccpVDZ computation of the waterwater interaction energy, using the three SAPT codes. 

Check that C++ Molecule class and qcdb molecule class are reading molecule input strings identically 

Test of SFX2C1e on Water ccpVDZDK. In this test the Dirac equation is solved in the uncontracted ccpVDZDK basis. The reference numbers are from Lan Cheng’s implementation in Cfour 

Lithium test for coverage 

DFCCSDL ccpVDZ energy for the H2O molecule. 

LCCD ccpVDZ gradient for the H2O molecule. 

OMP2 ccpVDZ energy for the H2O molecule. 

OMP3 ccpVDZ gradient for the NO radical 

RHF Density Matrix basedIntegral Screening Test for water 

RISCF ccpVTZ energy of water, with Zmatrix input and ccpVTZRI auxilliary basis. 

Extrapolated water energies 

SCF DZ allene geometry optimization, with Cartesian input, first in c2v symmetry, then in Cs symmetry from a starting point with a nonlinear central bond angle. 

DFMP2 ccpVDZ frozen core gradient of benzene, computed at the DFSCF ccpVDZ geometry 

MP2/augccpv[DT]Z many body energies of an arbitrary Helium complex Size vs cost tradeoff is rough here 

MP2 with a PBE0 reference computation 

Electrostatic potential and electric field evaluated on a grid around water. 

OMP2 ccpVDZ energy for the NO molecule. 

MkMRCCSD frequencies. \(^1A_1\) O$_3` state described using the Ms = 0 component of the singlet. Uses TCSCF orbitals. 

Sample HF/ccpVDZ H2O computation all derivatives 

Vibrational and thermo analysis of several water isotopologs. Demonstrates Hessian reuse for different temperatures, pressures, and isotopologs 

Singlepoint gradient, analytic and via finitedifferences of 21A1 state of H2O with EOMCCSD 

DFOMP2.5 ccpVDZ gradients for the H2O molecule. 

External potential calculation involving a TIP3P water and a QM water. Finite different test of the gradient is performed to validate forces. 

SCF with various combinations of pk/densityfitting, castup/nocastup, and spherical/cartesian settings. Demonstrates that puream setting is getting set by orbital basis for all df/castup parts of calc. Demonstrates that answer doesn’t depend on presence/absence of castup. Demonstrates (by comparison to castup2) that output file doesn’t depend on options (scf_type) being set global or local. This input uses local. 

Tests DFMP2 gradient in the presence of a dipole field 

DFOMP3 ccpVDZ energy for the H2O+ cation 

CI/MCSCF ccpvDZ properties for Potassium nitrate (rocket fuel!) 

ROHFCCSD/ccpVDZ \(^{3}B_1\) CH2 geometry optimization via analytic gradients 

SAPT0(ROHF) openshell computation of CN  Ne interaction energy First with junccpVDZ and density fitted integrals with ROHF Then with ccpVDZ and direct integrals, except for dispersion that is computed with ccpVDZri density fitting with ROHF. 

usapt example with empty beta due to frozen core 

OLCCD ccpVDZ gradient for the H2O molecule. 

631G** H2O+ Test CISD Energy Point 

OLCCD ccpVDZ energy with B3LYP initial guess for the NO radical 

This test case shows an example of running and analyzing a standard FSAPT0/junccpvdz procedure for HSG18dimer from the HSG database. 

ROHFCCSD ccpVDZ energy for the \(^2\Sigma^+\) state of the CN radical 

Triple and Singlet Oxygen energy SOSCF, also tests nonsymmetric density matrices 

SAPT(DFT) augccpVDZ interaction energy between Ne and Ar atoms. 

sapt0 of charged system in ECP basis set 

testing aligner on enantiomers based on Table 1 of 10.1021/ci100219f aka J Chem Inf Model 2010 50(12) 21292140 

631G** H2O Test CISD Energy Point 

Doublehybrid density functional B2PYLP. Reproduces portion of Table I in S. Grimme’s J. Chem. Phys 124 034108 (2006) paper defining the functional. 

OMP2.5 ccpVDZ energy for the H2O molecule. 

Density fitted MP2 ccPVDZ/ccpVDZRI computation of formic acid dimer binding energy using explicit specification of ghost atoms. This is equivalent to the dfmp2_1 sample but uses both (equivalent) specifications of ghost atoms in a manual counterpoise correction. 

MP2 ccpVDZ gradient for the NO radical 

check mixing ECP and nonECP orbital/fitting basis sets in a session 

631G** H2O CCSD optimization by energies, with ZMatrix input 

Extrapolated water energies  densityfitted version 

This test case shows an example of running the ISAPT0/junccpVDZ computation for 2,4pentanediol (targeting the intramolecular hydrogen bond between the two hydroxyl groups) The SIAO1 link partitioning algorithm is used. An FSAPT partitioning follows ISAPT. 

Cholesky decomposed REMP/ccpVDZ energies for the CO2 molecule. 

DFSCF ccpVDZ of benzenehydronium ion, scanning the dissociation coordinate with Python’s builtin loop mechanism. The geometry is specified by a Zmatrix with dummy atoms, fixed parameters, updated parameters, and separate charge/multiplicity specifiers for each monomer. Oneelectron properties computed for dimer and one monomer. 

Omega optimization for LRC functional wB97 on water 

SAPT(DFT) augccpVDZ interaction energy between Ne and Ar atoms. 

OMP2 ccpVDZ energy for the NO molecule. 

Example potential energy surface scan and CPcorrection for Ne2 

SCF STO3G finitedifferences frequencies from gradients for H2O 

SCF DZ finite difference frequencies by energies for C4NH4 

DFT integral algorithms test, performing wB97 RKS and UKS computations on water and its cation, using all of the different integral algorithms. This tests both the ERI and ERF integrals. 

Various constrained energy minimizations of HOOH with ccpvdz RHF Internalcoordinate constraints in internalcoordinate optimizations. 

The multiple guesses for DCT amplitudes for ODC12. 

631G H2O Test FCI Energy Point 

DFCCSD ccpVDZ energy for the H2O molecule. 

Secondorder SCF convergnece: Benzene 

This test case shows an example of running and analyzing a standard FSAPT0/junccpvdz procedure for phenol dimer from the S22 database. 

DFCCSD(T) ccpVDZ gradient for the NH molecule. 

MBIS calculation on NaCl 

SCF level shift on a CUHF computation 

tdcamb3lyp with DiskDF and method/basis specification 

Example of stateaveraged CASSCF for the C2 molecule 

631G H2O Test for coverage 

Computation of VMFCcorrected water trimer gradient (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

MP2 ccpVDZ gradient for the H2O molecule. 

Intercalls among python wrappers database, cbs, optimize, energy, etc. Though each call below functions individually, running them all in sequence or mixing up the sequence is aspirational at present. Also aspirational is using the intended types of gradients. 

MkMRCCSD single point. \(^3 \Sigma ^\) O2 state described using the Ms = 0 component of the triplet. Uses ROHF triplet orbitals. 

This test case shows an example of running the ISAPT0/augccpVDZ computation for a positively charged system, illustrating the cationpi interaction. The SIAO1 link partitioning algorithm is used. The system is taken from http://dx.doi.org/10.1016/j.comptc.2014.02.008 

RHF ccpVQZ energy for the BH molecule, with Cartesian input. 

ROHFEOMCCSD/DZ analytic gradient lowest \(^{2}B_1\) state of H2O+ (A1 excitation) 

DFOMP3 ccpVDZ gradients for the H2O+ cation. 

UFH and B3LYP ccpVQZ properties for the CH2 molecule. 

check that methods can act on single atom 

Similar to mints2, but using the BSE to specify the basis sets 

Test omega is setable updated wb97x_20,wb97x_03 to account for new BraggSlater radii 

UHF STO3G (Cartesian) and ccpVDZ (spherical) water Hessian test, against Psi3 reference values. This test should match RHF values exactly 

Test SCF dipole derivatives against old Psi3 reference values 

Test of SFX2C1e on Water uncontracted ccpVDZ The reference numbers are from Lan Cheng’s implementation in Cfour 

Unrestricted DFDCT ODC12 gradient for O2 with ccpVTZ/ccpVTZRI standard/auxiliary basis set 

Tests SCF gradient in the presence of a dipole field 

DFOMP2.5 ccpVDZ energy for the H2O molecule. 

DC06, DC12, ODC06 and ODC12 calculation for the He dimer. This performs a simultaneous update of the orbitals and cumulant, using DIIS extrapolation. Fourvirtual integrals are handled in the MO Basis. 

ROHF stability analysis check for CN with ccpVDZ. This test corresponds to the rohfstab test from Psi3. 

DFBP86D2 ccpVDZ frozen core gradient of S22 HCN updated ref gradient due to new BraggSlater radii 

MP3 ccpVDZ gradient for the NO radical 

FSAPT with external charge on dimer 

This is a shorter version if isapt1  does not do cube plots. See isapt1 for full details 

Restricted DFDCT ODC12 gradient for ethylene with ccpVDZ/ccpVDZRI standard/auxiliary basis set 

Benzene Dimer OutofCore HF/ccpVDZ 

631G* C2 Test RASCI Energy Point, testing two different ways of specifying the active space, either with the ACTIVE keyword, or with RAS1, RAS2, RESTRICTED_DOCC, and RESTRICTED_UOCC 

RHF ccpVDZ energy for water, automatically scanning the symmetric stretch and bending coordinates using Python’s builtin loop mechanisms. The geometry is specified using a Zmatrix with variables that are updated during the potential energy surface scan, and then the same procedure is performed using polar coordinates, converted to Cartesian coordinates. 

He2+ FCI/ccpVDZ Transition Dipole Moment 

631G H2O Test FCI Energy Point 

Tests SAPT0D corrections, with a variety of damping functions/parameters 

Test of SAD/Castup (mainly not dying due to file weirdness) 

BH single points, checking that program can run multiple instances of DETCI in a single input, without an intervening clean() call 

density fitted REMP/ccpVDZ energies for the CH3 radical 

A rangeseperated gradient for SO2 to test disk algorithms by explicitly setting low memory 

routing check on lccd, lccsd, cepa(0). 

ROHF and UHFBCCD(T)/ccpVDZ \(^{3}B_1\) CH2 singlepoint energy (fzc, MObasis \(\langle abcd \rangle\) ) 

LCCD ccpVDZ gradient for the NO radical 

reproduces dipole moments in J.F. Stanton’s “biorthogonal” JCP paper 

OMP2 ccpVDZ gradient for the NO radical 

Tests RHF CCSD(T)gradients 

RASCI/631G** H2O Energy Point 

Analytic SVWN frequencies, compared to finite difference values 

FSAPT0/junccpvdz procedure for methane dimer 

Various constrained energy minimizations of HOOH with ccpvdz RHF. Cartesiancoordinate constrained optimizations of HOOH in internals. 

Compute three IP and 2 EA’s for the PH3 molecule 

UHFCCSD(T) ccpVDZ frozencore energy for the \(^2\Sigma^+\) state of the CN radical, with Zmatrix input. 

H2O CISD/631G** Optimize Geometry by Energies 

MBIS calculation on H2O 

A demonstration of mixed Cartesian/ZMatrix geometry specification, using variables, for the benzenehydronium complex. Atoms can be placed using ZMatrix coordinates, whether they belong to the same fragment or not. Note that the Cartesian specification must come before the ZMatrix entries because the former define absolute positions, while the latter are relative. 

Analytic vs. finite difference DFSCF frequency test for water. 

Numpy interface testing 

comparison of DFMP2 and DLPNOMP2 with a CBS extrapolation 

cc3: RHFCCSD/631G** H2O geometry optimization and vibrational frequency analysis by finitedifferences of gradients 

Generation of NBO file 

density fitted OOREMP/ccpVDZ engrad single points for the H2O+ molecule. 

Scan fractional occupation of electrons updated values due to new BraggSlater radii 

Single point energies of multiple excited states with EOMCCSD 

An example of using BLAS and LAPACK calls directly from the Psi input file, demonstrating matrix multiplication, eigendecomposition, Cholesky decomposition and LU decomposition. These operations are performed on vectors and matrices provided from the Psi library. 

WaterArgon complex with ECP present; check of energies and forces. 

Superficial test of PubChem interface 

checks that all SAPT physical components (elst, exch, indc, disp) and total IE are being computed correctly for SAPT2+3(CCD)dMP2/augccpvdz and all lesser methods thereof. 

DCT calculation for the triplet O2 using ODC06 and ODC12 functionals. Only simultaneous algorithm is tested. 

DFMP2 frequency by difference of energies for H2O 

check all variety of options parsing 

RHF augccpVQZ energy for the BH molecule, with Cartesian input. Various gradients for a strained helium dimer and water molecule 

usapt example with empty beta 

DFBP86D2 ccpVDZ frozen core gradient of S22 HCN update ref gradient due to new BraggSlater radii 

This checks that all energy methods can run with a minimal input and set symmetry. 

Test of all different algorithms and reference types for SCF, on singlet and triplet O2, using the ccpVTZ basis set. 

EOMCC2/ccpVDZ on H2O2 with two excited states in each irrep 

OLCCD ccpVDZ energy with ROHF initial guess for the NO radical 

CASSCF/631G** energy point 

MP2/augccpvDZ many body energies of an arbitrary Helium complex, addressing 4body formulas 

tduhf test on triplet states of methylene (tda), wfn passing 

DFCCSD(T) ccpVDZ gradients for the H2O molecule. 

SAPT(DFT) augccpVDZ interaction energy between Ne and Ar atoms. 

check SP basis Fortran exponent parsing 

RHFBCCD(T)/631G** H2O singlepoint energy (fzc, MObasis \(\langle abcd \rangle\)) 

DFT JK ondisk test 

MkMRCCSD single point. \(^3 \Sigma ^\) O2 state described using the Ms = 0 component of the triplet. Uses ROHF triplet orbitals. 

SCF 631G(d) optimization of TS for HCN to HNC Performs finite difference hessian calculation. Then optimizes using previous orbitals for scf guess, in subsequent calculations. The last two displacements of the hessian break the plane of symemtry, This test confirms that only the reference geometry, with the correct symmetry, writes orbitals to disk. SCF will fail (ValidationError) otherwise. 

Test SFX2C1e with a static electric field on He augccpVTZ 

DFCCSD ccpVDZ gradients for the H2O molecule. 

Tests CCENERGY’s CCSD gradient in the presence of a dipole field 

This test case shows an example of running and analyzing a difference FSAPT0/junccpvdz procedure for phenol dimer from the S22 database. 

MOM excitation from LUMO HOMO+4 

Check flavors of B3LYP (b3lyp3/b3lyp5) against other programs 

CONV SCF 631G analytical vs finitedifference tests Tests UHF hessian code for Ca != Cb 

Various basis set extrapolation tests 

SAPT2+3 with S^inf exchind30 Geometries taken from the S66x10 database, the shortestrange point (R = 0.7 R_e) 

Test of the superposition of atomic densities (SAD) guess, using a highly distorted water geometry with a ccpVDZ basis set. This is just a test of the code and the user need only specify guess=sad to the SCF module’s (or global) options in order to use a SAD guess. The test is first performed in C2v symmetry, and then in C1. 

This checks that all energy methods can run with a minimal input and set symmetry. 

DC06 calculation for the O2 molecule (triplet ground state). This performs geometry optimization using twostep and simultaneous solution of the response equations for the analytic gradient. 

Multilevel computation of water trimer energy (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

SAPT2+(3) augccpVDZ computation of the formamide dimer interaction energy, using the augccpVDZJKFIT DF basis for SCF and augccpVDZRI for SAPT. This example uses frozen core as well as MP2 natural orbital approximations. 

Quick test of external potential in FSAPT (see fsapt1 for a real example) 

UHF>UHF stability analysis test for BH with ccpVDZ Test direct SCF with and without symmetry, test PK without symmetry 

SCF STO3G geometry optimzation, with Zmatrix input 

Tests analytic CC2 gradients 

DFT Functional Test for RangeSeperated Hybrids and Ghost atoms 

manybody different levels of theory on each body of helium tetramer 

apply linear fragmentation algorithm to a water cluster 

tdcamb3lyp with DiskDF and method/basis specification 

DFCCSD ccpVDZ gradients for the H2O molecule. 

Sample HF/ccpVDZ H2O computation 

CCSD dipole with userspecified basis set 

RHFCCSD(T) ccpVQZ frozencore energy of the BH molecule, with Cartesian input. This version tests the FROZEN_DOCC option explicitly 

MP2 ccpvDZ properties for Nitrogen oxide 

631G** H2O Test CISD Energy Point with subspace collapse 

ROHFEOMCCSD/DZ analytic gradient lowest \(^{2}A_1\) excited state of H2O+ (B1 excitation) 

RHFCCSDLR/ccpVDZ static polarizability of HOF 

CCSD/ccpVDZ optical rotation calculation (both gauges) on Cartesian H2O2 

apply linear fragmentation algorithm to a water cluster 

Test individual integral objects for correctness. 

DFT (LDA/GGA) test of custom implementations in: gga_superfuncs.py 

Various gradients for a strained helium dimer and water molecule 

check nonphysical masses possible 

631G** H2O Test RASSCF Energy Point will default to only singles and doubles in the active space 

A test of the basis specification. A benzene atom is defined using a ZMatrix containing dummy atoms and various basis sets are assigned to different atoms. The symmetry of the molecule is automatically lowered to account for the different basis sets. 

OMP2 ccpVDZ gradient for the H2O molecule. 

mtd/basis syntax examples 

Cholesky filter a complete basis 

tdwb97x excitation energies of singlet states of h2o, wfn passing 

631G** H2O+ Test CISD Energy Point 

RHFCC2LR/ccpVDZ optical rotation of H2O2. gauge = both, omega = (589 355 nm) 

DFOMP2 ccpVDZ gradients for the H2O molecule. 

Computation of CPcorrected water trimer gradient (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

Compute three IP and 2 EA’s for the PH3 molecule 

DFT Functional Test 

Density fitted MP2 energy of H2, using density fitted reference and automatic looping over ccpVDZ and ccpVTZ basis sets. Results are tabulated using the built in table functions by using the default options and by specifiying the format. 

RHF CCSD(T) ccpVDZ frozencore energy of C4NH4 Anion 

Test if the the guess read in the same basis converges. 

EOMCC3/ccpVTZ on H2O 

Fractional occupation with symmetry 

FSAPT with external charge on trimer 

CCSD Response for H2O2 

631G H2O Test FCI Energy Point 

DFT Functional Smoke Test 

EOMCC3(ROHF) on CH radical with userspecified basis and properties for particular root 

OMP3 ccpCVDZ energy with B3LYP initial guess for the NO radical 

Test method/basis with disk_df 

Computation of VMFCcorrected HF dimer Hessian 

CC2(UHF)/ccpVDZ energy of H2O+. 

EOMCC3(UHF) on CH radical with userspecified basis and properties for particular root 

Patch of a glycine with a methyl group, to make alanine, then DFSCF energy calculation with the ccpVDZ basis set 

UHFCCSD(T) ccpVDZ frozencore energy for the \(^2\Sigma^+\) state of the CN radical, with Zmatrix input. 

Maximum Overlap Method (MOM) Test. MOM is designed to stabilize SCF convergence and to target excited Slater determinants directly. 

OMP3 ccpVDZ energy for the H2O molecule 

CC3(UHF)/ccpVDZ H2O \(R_e\) geom from Olsen et al., JCP 104, 8007 (1996) 

NeXe dimer MP2 energies with ECP, with electrons correlated then frozen. 

DC06 calculation for the He dimer. This performs a simultaneous update of the orbitals and cumulant, using DIIS extrapolation. Fourvirtual integrals are handled in the AO Basis, using integrals stored on disk. 

integral conventional OOREMP/ccpVDZ engrad single points for the H2O molecule. single point energies were independently checked using the original wavels code 

Tests RHF/ROHF/UHF SCF gradients 

631G** H2O Test CISD Energy Point 

UHF Dipole Polarizability Test 

EOMCCSD/631g excited state transition data for water with two excited states per irrep 

RHFCC2LR/ccpVDZ dynamic polarizabilities of HOF molecule. 

External potential calculation involving a TIP3P water and a QM water for DFMP2. Finite different test of the gradient is performed to validate forces. 

Test initial SCF guesses on FH and FH+ in ccpVTZ basis 

MkMRCCSD(T) single point. \(^1A_1\) CH2 state described using the Ms = 0 component of the singlet. Uses RHF singlet orbitals. 

DFT (hybrids) test of implementations in: hybrid_superfuncs.py 

Restricted DFDCT ODC12 energies with linearly dependent basis functions 

This test case shows an example of running the ISAPT0/junccpVDZ computation for 2,4pentanediol (targeting the intramolecular hydrogen bond between the two hydroxyl groups) The SIAO1 link partitioning algorithm is used. 

File retention, docc, socc, and bond distances specified explicitly. 

Tests to determine full point group symmetry. Currently, these only matter for the rotational symmetry number in thermodynamic computations. 

ccpvdz H2O Test CEPA(1) Energy 

This test case shows an example of running and analyzing an FISAPT0/junccpvdz computation for 2,4pentanediol (targeting the intramolecular hydrogen bond between the two hydroxyl groups) 

CASSCF/631G** energy point 

RHF orbitals and density for water. 

631G H2O Test FCI Energy Point 

External potential calculation with one Ghost atom and one point charge at the same position. 

DFCCSD(T) ccpVDZ energy for the H2O molecule. 

Database calculation, so no molecule section in input file. Portions of the full databases, restricted by subset keyword, are computed by sapt0 and dfmp2 methods. 

Test case for some of the PSI4 outofcore codes. The code is given only 2.0 MB of memory, which is insufficient to hold either the A1 or B2 blocks of an ovvv quantity incore, but is sufficient to hold at least two copies of an oovv quantity incore. 

DFCCSD(T) ccpVDZ energy for the NH molecule. 

Allelectron MP2 631G** geometry optimization of water 

Advanced python example sets different sets of scf/postscf conv crit and check to be sure computation has actually converged to the expected accuracy. 

631G** H2O+ Test CISD Energy Point 

Compute the IRC for HCN <> NCH interconversion at the RHF/DZP level of theory. 

DFOMP3 ccpVDZ energy for the H2O molecule. 

CASSCF/631G** energy point 

DFCCD ccpVDZ energy for the H2O molecule. 

Test Gibbs free energies at 298 K of N2, H2O, and CH4. 

RHF 631G** energy of water, using the MCSCF module and Zmatrix input. 

Various extrapolated optimization methods for the H2 molecule 

RHF Linear Exchange Algorithm test for water 

Convergence of manybody gradients of different BSSE schemes 

SCF ccpVDZ geometry optimzation, with Zmatrix input 

B3LYP ccpVDZ geometry optimzation of phenylacetylene, starting from not quite linear structure updated reference due to new BraggSlater radii 

Various DCT analytic gradients for the O2 molecule with 631G basis set 

Optimize H2O HF/ccpVDZ 

Accesses basis sets, databases, plugins, and executables in noninstall locations 

DFSCF ccpVDZ multipole moments of benzene, up to 7th order and electrostatic potentials evaluated at the nuclear coordinates 

Ne atom RASCI/ccpVQZ Example of splitvirtual CISD[TQ] from Sherrill and Schaefer, J. Phys. Chem. XXX This uses a “primary” virtual space 3s3p (RAS 2), a “secondary” virtual space 3d4s4p4d4f (RAS 3), and a “tertiary” virtual space consisting of the remaining virtuals. First, an initial CISD computation is run to get the natural orbitals; this allows a meaningful partitioning of the virtual orbitals into groups of different importance. Next, the RASCI is run. The splitvirtual CISD[TQ] takes all singles and doubles, and all triples and quadruples with no more than 2 electrons in the secondary virtual subspace (RAS 3). If any electrons are present in the tertiary virtual subspace (RAS 4), then that excitation is only allowed if it is a single or double. 

SAPT2+3(CCD) augccpVDZ+midbond computation of the water dimer interaction energy, using the augccpVDZJKFIT DF basis for SCF and augccpVDZRI for SAPT. 

ADIIS test case, from 10.1063/1.3304922 

Various gradients for a strained helium dimer and water molecule 

Cholesky decomposed OOREMP/ccpVDZ energy for the H2O molecule. 

Sample UHF/631G** CH2 computation 

ROHFCCSD ccpVDZ frozencore energy for the \(^2\Sigma^+\) state of the CN radical, with Cartesian input. 

DFOMP3 ccpVDZ gradients for the H2O molecule. 

Spectroscopic constants of H2, and the full ci ccpVTZ level of theory 

SCF with various combinations of pk/densityfitting, castup/nocastup, and spherical/cartesian settings. Demonstrates that puream setting is getting set by orbital basis for all df/castup parts of calc. Demonstrates that answer doesn’t depend on presence/absence of castup. Demonstrates (by comparison to castup3) that output file doesn’t depend on options (scf_type) being set global or local. This input uses global. 

OMP2.5 ccpVDZ gradient for the H2O molecule. 

An example of using BLAS and LAPACK calls directly from the Psi input file, demonstrating 

Test of the superposition of atomic densities (SAD) guess, using a highly distorted water geometry with a ccpVDZ basis set. This is just a test of the code and the user need only specify guess=sad to the SCF module’s (or global) options in order to use a SAD guess. The test is first performed in C2v symmetry, and then in C1. 

check that CC is returning the same values btwn CC*, FNOCC, and DFOCC modules 

density fitted OOREMP/ccpVDZ engrad single points for the H2O+ molecule. 

Extrapolated water energies  conventional integrals version 

RHFODC12 analytic gradient computations for H2O use AO_BASIS=DISK and AO_BASIS=NONE, respectively. RHFODC06 analytic gradient computations for H2O use AO_BASIS=DISK and AO_BASIS=NONE, respectively. 

RHFCCSD/ccpVDZ energy of H2O partitioned into pair energy contributions. 

SOSOMP2 ccpVDZ geometry optimization for the H2O molecule. 

RHFCC2LR/ccpVDZ static polarizabilities of HOF molecule. 

631G(d) optimization of SF4 starting from linear bond angle that is not linear in the optimized structure but is in a symmetry plane of the molecule. 

Spinrestricted DC06 counterpart of dct1. 

MkMRCCSD(T) single point. \(^1A_1\) CH2 state described using the Ms = 0 component of the singlet. Uses RHF singlet orbitals. 

DCT calculation for the triplet O2 using DC06 and DC12. Only twostep algorithm is tested. 

DC06 calculation for the He dimer. This performs a twostep update of the orbitals and cumulant, using DIIS extrapolation. Fourvirtual integrals are handled in the MO Basis. 

Test computing values of basis functions (puream and nonpuream) at points 

SCF ccpVDZ geometry optimzation of ketene, starting from bent structure 

test roundtripness of dict repr for psi4.core.Molecule and qcdb.Molecule 

DF SCF 631G UHFl vs RHF test Tests DF UHF hessian code for Ca = Cb 

SCF STO3G finitedifference frequencies from energies for H2O 

Optimization followed by frequencies H2O HF/ccpVDZ 

SCF ccpVTZ geometry optimzation, with Zmatrix input 

Benzene vertical singlettriplet energy difference computation, using the PubChem database to obtain the initial geometry, which is optimized at the HF/STO3G level, before computing single point energies at the RHF, UHF and ROHF levels of theory. 

CASSCF/631G** energy point 

EOMCCSD/631g excited state transition data for water cation 

Test that Python Molecule class processes geometry like psi4 Molecule class. 

Various constrained energy minimizations of HOOH with ccpvdz RHF. For “fixed” coordinates, the final value is provided by the user. 

Transitionstate optimizations of HOOH to both torsional transition states. 

MP2.5 ccpVDZ gradient for the H2O molecule. 

UHFCCSD(T)/ccpVDZ \(^{3}B_1\) CH2 geometry optimization via analytic gradients 

DSDPBEP86 S22 Ammonia test 

conventional and densityfitting mp2 test of mp2 itself and setting scsmp2 

SAPT0 ccpVDZ computation of the etheneethyne interaction energy, using the ccpVDZJKFIT RI basis for SCF and ccpVDZRI for SAPT. Monomer geometries are specified using Cartesian coordinates. 

SCF level shift on a UHF computation 

OMP3 ccpCVDZ energy with ROHF initial guess for the NO radical 

OMP2 ccpVDZ energy for the NO molecule. 

OMP2.5 ccpVDZ energy for the H2O molecule. 

ROHFCCSD ccpVDZ frozencore energy for the \(^2\Sigma^+\) state of the CN radical, with Cartesian input. 

SOSOMP3 ccpVDZ geometry optimization for the H2O molecule. 

Test if the the guess read in the same basis converges. 

SAPT(DFT) augccpVDZ interaction energy between Ne and Ar atoms. 

Single point gradient of 12B2 state of H2O+ with EOMCCSD 

Test FNODFCCSD(T) energy 

OMP3 ccpVDZ gradient for the H2O molecule. 

updated dldf reference to new BraggSlater radii Dispersionless density functional (dlDF+D) internal match to Psi4 Extensive testing has been done to match supplemental info of Szalewicz et. al., Phys. Rev. Lett., 103, 263201 (2009) and Szalewicz et. al., J. Phys. Chem. Lett., 1, 550555 (2010) 

Sample UHF/ccpVDZ H2O computation on a doublet cation, using RHF/ccpVDZ orbitals for the closedshell neutral as a guess 

SAPT calculation on bimolecular complex where monomers are unspecified so driver autofragments it. Basis set and auxiliary basis sets are assigned by atom type. 

HF/ccpVDZ many body energies of an arbitrary noble gas trimer complex Size vs cost tradeoff is rough here 

comparison of DFMP2 and DLPNOMP2 with a cartesian basis set 

Single point energies of multiple excited states with EOMCCSD 

RHFCCSD(T) ccpVQZ frozencore energy of the BH molecule, with Cartesian input. After the computation, the checkpoint file is renamed, using the PSIO handler. 

TCSCF ccpVDZ energy of asymmetrically displaced ozone, with Zmatrix input. 

tduhf test on triplet states of methylene (rpa) 

DCT calculation for the NH3+ radical using the ODC12 and ODC13 functionals. This performs both simultaneous and QC update of the orbitals and cumulant using DIIS extrapolation. Fourvirtual integrals are first handled in the MO Basis for the first two energy computations. In the next computation ao_basis=disk algorithm is used, where the transformation of integrals for fourvirtual case is avoided. 

Benzene Dimer DFHF/ccpVDZ 

DFACCSD(T) ccpVDZ energy for the NH molecule. 

SCF level shift on an ROHF computation 

ROHF 631G** energy of the \(^{3}B_1\) state of CH2, with Zmatrix input. The occupations are specified explicitly. 

Extrapolated water energies 

Test fnocc with linear dependencies 

MkMRPT2 single point. \(^1A_1\) F2 state described using the Ms = 0 component of the singlet. Uses TCSCF singlet orbitals. 

Compute the dipole, quadrupole, and traceless quadrupoles for water. 

DFT Functional Test all values update for new BraggSlater radii 

Test of the superposition of atomic densities (SAD) guess, using a highly distorted water geometry with a ccpVDZ basis set. This is just a test of the code and the user need only specify guess=sad to the SCF module’s (or global) options in order to use a SAD guess. The test is first performed in C2v symmetry, and then in C1. 

RHFCCSD 631G** allelectron optimization of the H2O molecule 

SCF STO3G finitedifference tests 

CC3/ccpVDZ H2O \(R_e\) geom from Olsen et al., JCP 104, 8007 (1996) 

DFCCDL ccpVDZ energy for the H2O molecule. 

CCSD/sto3g optical rotation calculation (length gauge only) at two frequencies on methyloxirane 

SCSOMP2 ccpVDZ geometry optimization for the H2O molecule. 

Patch of a glycine with a methyl group, to make alanine, then DFSCF energy calculation with the ccpVDZ basis set 

MBIS calculation on OH (Expanded Arrays) 

Computation of VMFCcorrected water trimer Hessian (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

RKS Density Matrix basedIntegral Screening Test for benzene 

RHF/ccpvdzdecontract HCl singlepoint energy Testing the in line decontract option for basis sets 

EOMCCSD/ccpVDZ on H2O2 with two excited states in each irrep 

DF SCF 631G analytical vs finitedifference tests Tests DF UHF hessian code for Ca != Cb 

Density fitted MP2 ccPVDZ/ccpVDZRI computation of formic acid dimer binding energy using automatic counterpoise correction. Monomers are specified using Cartesian coordinates. 

H2 with tiny basis set, to test basis set parser’s handling of integers 

Symmetry tests for a range of molecules. This doesn’t actually compute any energies, but serves as an example of the many ways to specify geometries in Psi4. 

MkMRCCSD(T) single point. \(^1A_1\) O$_3` state described using the Ms = 0 component of the singlet. Uses TCSCF orbitals. 

integral conventional REMP/ccpVDZ energies for the H2O molecule. results were independently verified against the initial wavels implementation 

Test QCISD(T) for H2O/ccpvdz Energy 

Cholesky decomposed REMP/ccpVDZ energies for the CH3 radical 

integral conventional OOREMP/ccpVDZ engrad single points for the H2O molecule. 

density fitted REMP/ccpVDZ energies for the CO2 molecule. 

Test FNODFCCSD(T) energy 

Frozencore CCSD(ROHF)/ccpVDZ on CN radical with diskbased AO algorithm 

MBIS calculation on H2O 

Test G2 method for H2O 

Test of SFX2C1e on water uncontracted ccpVDZDK The reference numbers are from Lan Cheng’s implementation in Cfour 

UHF and ROHF Linear Exchange Algorithm test for benzyl cation 

RHF STO3G dipole moment computation, performed by applying a finite electric field and numerical differentiation. 

sapt example with orbital freezing with alkali metal and dMP2 

He Dimer VV10 functional test. notes: DFT_VV10_B/C overwrites the NL_DISPERSION_PARAMETERS tuple updated ‘bench’ reference values for new BraggSlater radii. 

SCF/ccpVDZ optimization example with frozen cartesian 

631G(d) optimization of SF4 starting from linear bond angle that is not linear in the optimized structure but is in a symmetry plane of the molecule. 

Tests OMP2 gradient in the presence of a dipole field 

Test case for Binding Energy of C4H5N (Pyrrole) with CO2 using MP2/def2TZVPP 

Check that basis sets can be input with explicit angular momentum format 

BHH2+ FCI/ccpVDZ Transition Dipole Moment 

DFMP2 ccpVDZ gradients for the H2O molecule. 

Triple and Singlet Oxygen energy SOSCF, also tests nonsymmetric density matrices 

OLCCD ccpVDZ energy for the H2O molecule. 

A general test of the MintsHelper function 

SCF level shift on an RKS computation 

SAPT0 augccpVTZ computation of the charge transfer energy of the water dimer. 

OMP2.5 ccpVDZ gradient for the NO radical 

Compute the dipole polarizability for water with custom basis set. 

RHF interaction energies using nbody and cbs parts of the driver Ne dimer with mp2/v[dt]z + d:ccsd(t)/vdz 

OMP2 ccpVDZ energy with ROHF initial guess orbitals for the NO radical 

RHFCC2LR/ccpVDZ optical rotation of H2O2. gauge = length, omega= (589 355 nm) 

This checks that all energy methods can run with a minimal input and set symmetry. 

CASSCF/631G** energy point 

CASSCF/631G** energy point 

wB97XD test for a large UKS molecule update ref gradient due to new BraggSlater radii 

check distributed driver is correctly passing function kwargs 

DFMP2 ccpVDZ gradients for the H2O molecule. 

Tests SAPT0D corrections, with a variety of damping functions/parameters 

test FCIDUMP functionality for rhf/uhf 

SCF STO3G geometry optimzation, with Zmatrix input, by finitedifferences 

WaterArgon complex with ECP present; check of UHF Hessian 

Frequencies for H2O B3LYP/631G* at optimized geometry 

Tests all grid pruning options available and screening of small weights. Check against grid size. 

Kr–Kr nocp energies with allelectron basis set to check frozen core 

Matches Table II aCCSD(T)/ccpVDZ H2O @ 2.5 * Re value from Crawford and Stanton, IJQC 98, 601611 (1998). 

UHFODC12 and RHFODC12 singlepoint energy for H2O. This performs a simultaneous update of orbitals and cumulants, using DIIS extrapolation. Fourvirtual integrals are handled in the AO basis, where integral transformation is avoided. In the next RHFODC12 computation, AO_BASIS=NONE is used, where fourvirtual integrals are transformed into MO basis. 

test scf castup with custom basis sets 

RHFEOMCC2/ccpVDZ lowest two states of each symmetry of H2O. 

ROHFEOMCCSD/DZ on the lowest two states of each irrep in \(^{3}B_1\) CH2. 

Various constrained energy minimizations of HOOH with ccpvdz RHF. Cartesiancoordinate constrained optimizations of HOOH in Cartesians. 

DFT Functional Test 

Single point gradient of 12B1 state of H2O+ with EOMCCSD 

631G** UHF CH2 3B1 optimization. Uses a ZMatrix with dummy atoms, just for demo and testing purposes. 

OMP2 ccpVDZ energy for the NO molecule. 

Test FNOQCISD(T) computation 

CCSD/ccpVDZ optical rotation calculation (length gauge only) on Zmat H2O2 

MBIS calculation on OH radical 

DCT calculation for the HF+ using DC06 functional. This performs both twostep and simultaneous update of the orbitals and cumulant using DIIS extrapolation. Fourvirtual integrals are first handled in the MO Basis for the first two energy computations. In the next two the ao_basis=disk algorithm is used, where the transformation of integrals for fourvirtual case is avoided. The computation is then repeated using the DC12 functional with the same algorithms. 

Extrapolated energies with delta correction 

RHF orbitals and density for water. 

DFCCSD(AT) ccpVDZ energy for the H2O molecule. 

A test of the basis specification. Various basis sets are specified outright and in blocks, both orbital and auxiliary. Constructs libmints BasisSet objects through the constructor that calls qcdb.BasisSet infrastructure. Checks that the resulting bases are of the right size and checks that symmetry of the Molecule observes the basis assignment to atoms. 

MP3 ccpVDZ gradient for the H2O molecule. 

MP2.5 ccpVDZ gradient for the NO radical 

tdwb97x singlet excitation energies of methylene (tda) 

CC3(ROHF)/ccpVDZ H2O \(R_e\) geom from Olsen et al., JCP 104, 8007 (1996) 

Vibrational and thermo analysis of water trimer (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

SCSOMP3 ccpVDZ geometry optimization for the H2O molecule. 

DFOMP2.5 ccpVDZ energy for the H2O+ cation 

comparison of DFMP2 and DLPNOMP2 

CASSCF/631G** energy point. Check energy with frozen core/virtual orbs. after semicanonicalization. 

force occupations in scf 

Example of stateaveraged CASSCF for the C2 molecule see C. D. Sherrill and P. Piecuch, J. Chem. Phys. 122, 124104 (2005) 

MP(n)/augccpVDZ BH Energy Point, with n=219. Compare against M. L. Leininger et al., J. Chem. Phys. 112, 9213 (2000) 

A very quick correctness test of FSAPT (see fsapt1 for a real example) 

integral conventional unrestricted REMP/ccpVDZ energies for the H2O+ molecule. results were independently verified against the initial wavels implementation 

OMP2 ccpVDZ energy for the NO radical 

Test LDA stability analysis against QChem. 

ROHF frontier orbitals of CH2(s) and CH2(t). 

Frozencore CCSD(T)/ccpVDZ on C4H4N anion with disk ao algorithm 

Tests the Psi4 SFSAPT code 

MOM excitation from LUMO HOMO+3 

OMP2 ccpVDZ energy for the H2O molecule. 

Carbon/UHF FractionallyOccupied SCF Test Case 

HF and DFT variants singlepoints on zmat methane, mostly to test that PSI variables are set and computed correctly. Now also testing that CSX harvesting PSI variables correctly update ref_dft_2e/xc due to new BraggSlater radii 

DFT custom functional test 

Single point gradient of 11B2 state of H2O with EOMCCSD 

SAPT(DFT) augccpVDZ computation for the water dimer interaction energy. 

Analytic UKS SVWN frequencies, compared to finite difference values 

RHFCC2LR/STO3G optical rotation of (S)methyloxirane. gauge = both, omega = (589 355 nm) 

Tests CAM gradients with and without XC pieces to narrow grid error 

Computation of NoCPcorrected water trimer gradient (geometry from J. Chem. Theory Comput. 11, 21262136 (2015)) 

wB97XD ccpVDZ gradient of S22 HCN update df/pk_ref values due to new BraggSlater radii 

MkMRCCSD(T) single point. \(^1A_1\) CH2 state described using the Ms = 0 component of the singlet. Uses RHF singlet orbitals. 

analog of fsaptextabc with molecule and external potentials in Bohr 

Test parsed and exotic calls to energy() like zapt4, mp2.5, and cisd are working 

Tests RHF CCSD(T)gradients 

CCSD/sto3g optical rotation calculation (both gauges) at two frequencies on methyloxirane 

OMP2 ccpVDZ energy for the H2O molecule. 

WaterArgon complex with ECP present; check of RHF Hessian 

SCF DZ allene geometry optimzation, with Cartesian input 

Compute the IRC for HOOH torsional rotation at the RHF/DZP level of theory. 

OMP2 ccpVDZ energy for the H2O molecule. 

LibXC density screening test. Tests empty, Conly, Xonly and XC superfunctionals. ‘super_mix’ showcases how to use different screening values for X and C parts. SCF will fail or crash (nans) without screening! 

OLCCD ccpVDZ freqs for C2H2 

DFMP2 frequency by difference of energies for H2O 

Test SAD SCF guesses on noble gas atom 

SAPT0 openshell computation of H2OHO2 interaction energy First with ccpVDZ and density fitted integrals with UHF Then with 631g and direct integrals, except for dispersion that is computed with ccpVDZri density fitting with UHF. 

SCF/sto3g optimization with a hessian every step 

SAPT0 with S^inf exchdisp20 

ROHFCCSD(T) ccpVDZ frozencore energy for the \(^2\Sigma^+\) state of the CN radical, with Cartesian input. 

ZAPT(n)/631G NH2 Energy Point, with n=225 

UHFCCSD/ccpVDZ \(^{3}B_1\) CH2 geometry optimization via analytic gradients 

MBIS calculation on ZnO 

DFMP2 ccpVDZ gradient for the NO molecule. 

CCSD/ccpVDZ dipole polarizability at two frequencies 

EDIIS test case from 10.1063/1.1470195 

Example SAPT computation for ethene*ethine (i.e., ethylene*acetylene), test case 16 from the S22 database 

ccpvdz H2O Test ACPF Energy/Properties 

DFCCSD ccpVDZ gradient for the NH molecule. 

ccpvdz H2O Test coupledpair CISD against DETCI CISD 

OLCCD ccpVDZ gradient for the NO radical 

Vibrational and thermo analysis of several water isotopologs. Demonstrates Hessian reuse for different temperatures and pressures but not for different isotopologs. 

density fitted OOREMP/ccpVDZ engrad single points for the H2O molecule. 

SCF DZ finite difference frequencies by gradients for C4NH4 

optimization with method defined via cbs 

ROHFCCSD(T) ccpVDZ energy for the \(^2\Sigma^+\) state of the CN radical, with Zmatrix input. 

UHF gradient for a oneelectron system (no beta electrons). 

RHFCC2LR/STO3G optical rotation of (S)methyloxirane. gauge = length, omega = (589 355 nm) 

RHF STO3G (Cartesian) and ccpVDZ (spherical) water Hessian test, against Psi3 reference values. 

RKS Linear Exchange Algorithm test for benzene 

SAPT0 augccpVDZ computation of the benzenemethane interaction energy, using the augpVDZJKFIT DF basis for SCF, the augccpVDZRI DF basis for SAPT0 induction and dispersion, and the augpVDZJKFIT DF basis for SAPT0 electrostatics and induction. This example uses frozen core as well as asyncronous I/O while forming the DF integrals and CPHF coefficients. 

631G** H2O Test RASSCF Energy Point will default to only singles and doubles in the active space 