PSI Variables by Alpha¶

Note

Lowercase letters in PSI variable names represent portions of the variable name that vary by root number, calculation order, etc. See text for fuller description.

(T) CORRECTION ENERGY¶: The coupled-cluster perturbative triples correction [H].

A-(T) CORRECTION ENERGY¶: The coupled-cluster asymmetric perturbative triples correction [H].

MP4(T) CORRECTION ENERGY¶: The MP4 triples component [H]. Quantity is second right-hand term in Eq. (2).

AAA (T) CORRECTION ENERGY¶
AAB (T) CORRECTION ENERGY¶
ABB (T) CORRECTION ENERGY¶
BBB (T) CORRECTION ENERGY¶: Spin components of the UHF-based coupled-cluster perturbative triples correction [H].

ACPF DIPOLE X¶
ACPF DIPOLE Y¶
ACPF DIPOLE Z¶: The three components of the dipole [Debye] for the averaged coupled-pair functional level of theory.

ACPF QUADRUPOLE XX¶
ACPF QUADRUPOLE XY¶
ACPF QUADRUPOLE XZ¶
ACPF QUADRUPOLE YY¶
ACPF QUADRUPOLE YZ¶
ACPF QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the averaged coupled-pair functional level of theory.

ACPF TOTAL ENERGY¶
ACPF CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the averaged coupled-pair functional level of theory.

AQCC DIPOLE X¶
AQCC DIPOLE Y¶
AQCC DIPOLE Z¶: The three components of the dipole [Debye] for the averaged quadratic coupled-cluster level of theory.

AQCC QUADRUPOLE XX¶
AQCC QUADRUPOLE XY¶
AQCC QUADRUPOLE XZ¶
AQCC QUADRUPOLE YY¶
AQCC QUADRUPOLE YZ¶
AQCC QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the averaged quadratic coupled-cluster level of theory.

AQCC TOTAL ENERGY¶
AQCC CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the averaged quadratic coupled-cluster level of theory.

BRUECKNER CONVERGED¶: Value 1 (0) when the Brueckner orbitals have (have not) converged.

CBS TOTAL ENERGY¶
CBS CORRELATION ENERGY¶
CBS REFERENCE ENERGY¶: The total electronic energy [H] and its breakdown into reference total energy [H] and correlation correction components [H] for the compound method requested through cbs().

CC ROOT n TOTAL ENERGY¶: The total electronic energy [H] for the requested coupled cluster level of theory and root n (numbering starts at GS = 0).

CC TOTAL ENERGY¶
CC CORRELATION ENERGY¶

CC2 TOTAL ENERGY¶
CC2 CORRELATION ENERGY¶
CC3 TOTAL ENERGY¶
CC3 CORRELATION ENERGY¶
CC4 TOTAL ENERGY¶
CC4 CORRELATION ENERGY¶
CCnn TOTAL ENERGY¶
CCnn CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the requested approximate coupled-cluster (CC2, CC3, up to CCnn) level of theory.

CC DIPOLE X¶
CC DIPOLE Y¶
CC DIPOLE Z¶: The three components of the dipole [Debye] for the requested coupled cluster level of theory and root.

CC QUADRUPOLE XX¶
CC QUADRUPOLE XY¶
CC QUADRUPOLE XZ¶
CC QUADRUPOLE YY¶
CC QUADRUPOLE YZ¶
CC QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the requested coupled cluster level of theory and root.

CCSD TOTAL ENERGY¶
CCSD CORRELATION ENERGY¶
CCSDT TOTAL ENERGY¶
CCSDT CORRELATION ENERGY¶
CCSDTQ TOTAL ENERGY¶
CCSDTQ CORRELATION ENERGY¶
CCn TOTAL ENERGY¶
CCn CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the requested full coupled-cluster (CCSD, CCSDT, up to CCn) level of theory.

CCSD(T) TOTAL ENERGY¶
CCSD(T) CORRELATION ENERGY¶
A-CCSD(T) TOTAL ENERGY¶
A-CCSD(T) CORRELATION ENERGY¶
CCSDT(Q) TOTAL ENERGY¶
CCSDT(Q) CORRELATION ENERGY¶
CC(n-1)(n) TOTAL ENERGY¶
CC(n-1)(n) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the perturbatively corrected coupled-cluster (CCSD(T), a-CCSD(T), CCSDT(Q), up to CC(n-1)(n) level of theory.

CCSDT-1a TOTAL ENERGY¶
CCSDT-1a CORRELATION ENERGY¶
CCSDTQ-1a TOTAL ENERGY¶
CCSDTQ-1a CORRELATION ENERGY¶
CCn-1a TOTAL ENERGY¶
CCn-1a CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the approximate coupled-cluster (CCSD(T)-1a, CCSDT(Q)-1a, up to CCn-1a) level of theory.

CCSDT-1b TOTAL ENERGY¶
CCSDT-1b CORRELATION ENERGY¶
CCSDTQ-1b TOTAL ENERGY¶
CCSDTQ-1b CORRELATION ENERGY¶
CCn-1b TOTAL ENERGY¶
CCn-1b CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the approximate coupled-cluster (CCSD(T)-1b, CCSDT(Q)-1b, up to CCn-1b) level of theory.

CCSDT-3 TOTAL ENERGY¶
CCSDT-3 CORRELATION ENERGY¶
CCSDTQ-3 TOTAL ENERGY¶
CCSDTQ-3 CORRELATION ENERGY¶
CCn-3 TOTAL ENERGY¶
CCn-3 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the approximate coupled-cluster (CCSD(T)-3, CCSDT(Q)-3, up to CCn-3) level of theory.

CCSD(T)_L TOTAL ENERGY¶
CCSD(T)_L CORRELATION ENERGY¶
CCSDT(Q)_L TOTAL ENERGY¶
CCSDT(Q)_L CORRELATION ENERGY¶
CC(n-1)(n)_L TOTAL ENERGY¶
CC(n-1)(n)_L CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the approximate coupled-cluster (CCSD(T)_L, CCSDT(Q)_L, up to CC(n-1)(n)L level of theory.

CEPA(0) DIPOLE X¶
CEPA(0) DIPOLE Y¶
CEPA(0) DIPOLE Z¶: The three components of the dipole [Debye] for the coupled electron pair approximation variant 0 level of theory.

CEPA(0) QUADRUPOLE XX¶
CEPA(0) QUADRUPOLE XY¶
CEPA(0) QUADRUPOLE XZ¶
CEPA(0) QUADRUPOLE YY¶
CEPA(0) QUADRUPOLE YZ¶
CEPA(0) QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the coupled electron pair approximation variant 0 level of theory.

CEPA(0) TOTAL ENERGY¶
CEPA(0) CORRELATION ENERGY¶
CEPA(1) TOTAL ENERGY¶
CEPA(1) CORRELATION ENERGY¶
CEPA(2) TOTAL ENERGY¶
CEPA(2) CORRELATION ENERGY¶
CEPA(3) TOTAL ENERGY¶
CEPA(3) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the requested variant of coupled electron pair approximation level of theory.

CI DIPOLE X¶
CI DIPOLE Y¶
CI DIPOLE Z¶: The three components of the dipole [Debye] for the requested configuration interaction level of theory and root.

CI QUADRUPOLE XX¶
CI QUADRUPOLE XY¶
CI QUADRUPOLE XZ¶
CI QUADRUPOLE YY¶
CI QUADRUPOLE YZ¶
CI QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the requested configuration interaction level of theory and root.

CI ROOT n -> ROOT m DIPOLE X¶
CI ROOT n -> ROOT m DIPOLE Y¶
CI ROOT n -> ROOT m DIPOLE Z¶: The three components of the transition dipole [Debye] between roots n and m for the requested configuration interaction level of theory.

CI ROOT n -> ROOT m QUADRUPOLE XX¶
CI ROOT n -> ROOT m QUADRUPOLE XY¶
CI ROOT n -> ROOT m QUADRUPOLE XZ¶
CI ROOT n -> ROOT m QUADRUPOLE YY¶
CI ROOT n -> ROOT m QUADRUPOLE YZ¶
CI ROOT n -> ROOT m QUADRUPOLE ZZ¶: The three components of the transition quadrupole [Debye Ang] between roots n and m for the requested configuration interaction level of theory.

CI ROOT n DIPOLE X¶
CI ROOT n DIPOLE Y¶
CI ROOT n DIPOLE Z¶: The three components of the dipole [Debye] for the requested configuration interaction level of theory and root n.

CI ROOT n QUADRUPOLE XX¶
CI ROOT n QUADRUPOLE XY¶
CI ROOT n QUADRUPOLE XZ¶
CI ROOT n QUADRUPOLE YY¶
CI ROOT n QUADRUPOLE YZ¶
CI ROOT n QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the requested configuration interaction level of theory and root n.

CI ROOT n TOTAL ENERGY¶
CI ROOT n CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the requested configuration interaction level of theory and root n (numbering starts at 1).

CI STATE-AVERAGED TOTAL ENERGY¶
CI STATE-AVERAGED CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for state-averaged CI/CASSCF levels of theory.

CI TOTAL ENERGY¶
CI CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the requested configuration interaction level of theory and root.

CISD DIPOLE X¶
CISD DIPOLE Y¶
CISD DIPOLE Z¶: The three components of the dipole [Debye] for the configuration interaction singles and doubles level of theory and root.

CISD QUADRUPOLE XX¶
CISD QUADRUPOLE XY¶
CISD QUADRUPOLE XZ¶
CISD QUADRUPOLE YY¶
CISD QUADRUPOLE YZ¶
CISD QUADRUPOLE ZZ¶: The six components of the quadrupole [Debye Ang] for the configuration interaction singles and doubles level of theory and root.

CISD TOTAL ENERGY¶
CISD CORRELATION ENERGY¶
CISDT TOTAL ENERGY¶
CISDT CORRELATION ENERGY¶
CISDTQ CORRELATION ENERGY¶
CISDTQ TOTAL ENERGY¶
CIn CORRELATION ENERGY¶
CIn TOTAL ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the labeled configuration interaction level of theory and root. n is CI order for n > 4.

CP-CORRECTED 2-BODY INTERACTION ENERGY¶: The interaction energy [H] considering only two-body interactions, computed with counterpoise correction. Related variable UNCP-CORRECTED 2-BODY INTERACTION ENERGY.

$E_{\text{IE}} = E_{dimer} - \sum_{monomer}^{n}{E_{monomer}^{\text{CP}}}$

CURRENT CORRELATION ENERGY¶: The correlation energy [H] corresponding to the CURRENT ENERGY variable.

CURRENT ENERGY¶: The total electronic energy [H] of the most recent stage of a calculation (frequently overwritten). This is the quantity tracked by the geometry optimizer.

CURRENT REFERENCE ENERGY¶: The total electronic energy [H] of the reference stage corresponding to the CURRENT ENERGY variable.

db_name DATABASE MEAN ABSOLUTE DEVIATION¶: The mean absolute deviation [kcal mol^-1] of the requested method name from the stored reference values for the requested reactions in database db_name. If no reference is available, this will be a large and nonsensical value.

$\frac{1}{n}\sum_{rxn}^{n}{| \textsf{\textsl{name}}_{rxn}-\text{REF}_{rxn} | }$

db_name DATABASE MEAN SIGNED DEVIATION¶: The mean deviation [kcal mol^-1] of the requested method name from the stored reference values for the requested reactions in database db_name. If no reference is available, this will be a large and nonsensical value.

$\frac{1}{n}\sum_{rxn}^{n}{\textsf{\textsl{name}}_{rxn}-\text{REF}_{rxn}}$

db_name DATABASE ROOT-MEAN-SQUARE SIGNED DEVIATION¶: The rms deviation [kcal mol^-1] of the requested method name from the stored reference values for the requested reactions in database db_name. If no reference is available, this will be a large and nonsensical value.

$\sqrt{\frac{1}{n}\sum_{rxn}^{n}{(\textsf{\textsl{name}}_{rxn}-\text{REF}_{rxn})^2}}$

DFT FUNCTIONAL TOTAL ENERGY¶: The total electronic energy [H] for the underlying functional of the requested DFT method, without any dispersion correction; the first four terms in Eq. (4) or (1). Quantity $E_{\text{FCTL}}$ in Eqs. (4) and (1). Unless the method includes a dispersion correction, this quantity is equal to SCF TOTAL ENERGY.

DFT TOTAL ENERGY¶

The total electronic energy [H] for the requested DFT method, $E_{\text{DFT}}$ in Eq. (1).

(1) $\begin{align*} E_{\text{DFT}} & = E_{NN} + E_{1e^-} + E_{2e^-} + E_{xc} + E_{\text{-D}} + E_{\text{DH}} \\ & = E_{\text{FCTL}} + E_{\text{-D}} + E_{\text{DH}} \\ & = E_{\text{SCF}} + E_{\text{DH}} \end{align*}$

Unless the method is a DFT double-hybrid, this quantity is equal to SCF TOTAL ENERGY. If the method is neither a double-hybrid, nor dispersion corrected, this quantity is equal to DFT FUNCTIONAL TOTAL ENERGY.

DFT XC ENERGY¶: The functional energy contribution [H] to the total SCF energy (DFT only). Quantity $E_{xc}$ in Eqs. (4) and (1).

DISPERSION CORRECTION ENERGY¶: The dispersion correction [H] appended to an underlying functional when a DFT-D method is requested. Quantity $E_{\text{-D}}$ in Eqs. (4) and (1).

DOUBLE-HYBRID CORRECTION ENERGY¶: The scaled MP2 correlation energy correction [H] appended to an underlying functional when a DH-DFT method is requested. Quantity $E_{\text{DH}}$ in Eq. (1).

FCI TOTAL ENERGY¶
FCI CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the full configuration interaction level of theory.

HF TOTAL ENERGY¶: The total electronic energy [H] for the Hartree–Fock method, without any dispersion correction; the first three (or four, since $E_{xc} = 0$ ) terms in Eq. (4). Quantity $E_{\text{HF}}$ in Eq. (4).

LCC2 (+LMP2) TOTAL ENERGY¶: The total electronic energy [H] for the local CC2 level of theory.

LCCSD (+LMP2) TOTAL ENERGY¶: The total electronic energy [H] for the local CCSD level of theory.

MP2 TOTAL ENERGY¶
MP2 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the MP2 level of theory.

MP2.5 TOTAL ENERGY¶
MP2.5 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the MP2.5 level of theory.

MP3 TOTAL ENERGY¶
MP3 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the MP3 level of theory.

MP4(SDQ) TOTAL ENERGY¶
MP4(SDQ) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the MP4 singles, doubles, quadruples level of theory. Quantity MP4(SDQ) CORRELATION ENERGY is first right-hand term in Eq. (2).

MP4 TOTAL ENERGY¶
MP4 CORRELATION ENERGY¶
MP4(SDTQ) TOTAL ENERGY¶
MP4(SDTQ) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the full MP4 level of theory. Quantity MP4 CORRELATION ENERGY / MP4(SDTQ) CORRELATION ENERGY is left-hand term in Eq. (2).

(2) $E_{\text{MP4}} = E_{\text{MP4(SDQ)}} + E_{\text{MP4(T)}}$

MPn TOTAL ENERGY¶
MPn CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the labeled Möller–Plesset perturbation theory level. n is MP perturbation order.

NUCLEAR REPULSION ENERGY¶: The nuclear repulsion energy contribution [H] to the total SCF energy. Quantity $E_{NN}$ in Eq. (4).

(3) $E_{NN} = \sum_{i, j<i}^{N_{atom}}\frac{Z_i Z_j}{|\mathbf{R}_i - \mathbf{R}_j|}$

OCEPA(0) TOTAL ENERGY¶
OCEPA(0) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the orbital-optimized CEPA(0) level of theory.

OMP2 TOTAL ENERGY¶
OMP2 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the orbital-optimized MP2 level of theory.

OMP3 TOTAL ENERGY¶
OMP3 CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the orbital-optimized MP3 level of theory.

ONE-ELECTRON ENERGY¶: The one-electron energy contribution [H] to the total SCF energy. Quantity $E_{1e^-}$ in Eq. (4).

QCISD TOTAL ENERGY¶
QCISD CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the quadratic configuration interaction singles and doubles level of theory.

QCISD(T) TOTAL ENERGY¶
QCISD(T) CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the quadratic configuration interaction singles and doubles with perturbative triples correction level of theory.

SAPT DISP ENERGY¶
SAPT ELST ENERGY¶
SAPT EXCH ENERGY¶
SAPT IND ENERGY¶: Respectively, the dispersion, electrostatics, exchange, and induction components of the total electronic interaction energy [H] for the the requested SAPT level of theory. The sum of these four components yields SAPT ENERGY.

SAPT ENERGY¶: The total electronic interaction energy [H] for the requested SAPT level of theory.

SAPT SAPT0 ENERGY¶
SAPT SAPT2 ENERGY¶
SAPT SAPT2+ ENERGY¶
SAPT SAPT2+(3) ENERGY¶
SAPT SAPT2+3 ENERGY¶: The total electronic interaction energy [H] for the labeled SAPT level of theory.

SAPT SAPT2+(CCD) ENERGY¶
SAPT SAPT2+(3)(CCD) ENERGY¶
SAPT SAPT2+3(CCD) ENERGY¶: The total electronic interaction energy [H] for the labeled SAPT level of theory that incorporates coupled-cluster dispersion.

SCF DIPOLE X¶
SCF DIPOLE Y¶
SCF DIPOLE Z¶: The three components of the SCF dipole [Debye].

SCF QUADRUPOLE XX¶
SCF QUADRUPOLE XY¶
SCF QUADRUPOLE XZ¶
SCF QUADRUPOLE YY¶
SCF QUADRUPOLE YZ¶
SCF QUADRUPOLE ZZ¶: The six components of the SCF quadrupole [Debye Ang].

SCF TOTAL ENERGY¶

The total electronic energy [H] of the SCF stage of the calculation. The CORRELATION ENERGY variables from subsequent stages of a calculation are often the corresponding TOTAL ENERGY variables less this quantity. Constructed from Eq. (4), where this quantity is $E_{\text{SCF}}$ .

(4) $\begin{align*} E_{\text{SCF}} & = E_{NN} + E_{1e^-} + E_{2e^-} + E_{xc} + E_{\text{-D}} \\ & = E_{\text{FCTL/HF}} + E_{\text{-D}} \end{align*}$

Unless the method includes a dispersion correction, this quantity is equal to HF TOTAL ENERGY (for HF) or DFT FUNCTIONAL TOTAL ENERGY (for DFT). Unless the method is a DFT double-hybrid, this quantity is equal to DFT TOTAL ENERGY.

TWO-ELECTRON ENERGY¶: The two-electron energy contribution [H] to the total SCF energy. Quantity $E_{2e^-}$ in Eq. (4).

UNCP-CORRECTED 2-BODY INTERACTION ENERGY¶: The interaction energy [H] considering only two-body interactions, computed without counterpoise correction. Related variable CP-CORRECTED 2-BODY INTERACTION ENERGY.

$E_{\text{IE}} = E_{dimer} - \sum_{monomer}^{n}{E_{monomer}^{\text{unCP}}}$

ZAPTn TOTAL ENERGY¶
ZAPTn CORRELATION ENERGY¶: The total electronic energy [H] and correlation energy component [H] for the labeled Z-averaged perturbation theory level. n is ZAPT perturbation order.

PSI Variables by Alpha¶

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