Energy¶

energy(name[, bypass_scf, molecule])[source]¶

Function to compute the single-point electronic energy.

Returns:	(float) Total electronic energy in Hartrees. SAPT returns interaction energy.
Psi variables:

name	calls method
scf	Hartree–Fock (HF) or density functional theory (DFT)
mp2	2nd-order Moller-Plesset perturbation theory (MP2)
df-mp2	MP2 with density fitting
conv-mp2	conventional MP2 (non-density-fitting)
dcft	density cumulant functional theory
mcscf	multiconfigurational self consistent field (SCF)
sapt0	0th-order symmetry adapted perturbation theory (SAPT)
sapt2	2nd-order SAPT, traditional definition
sapt2+	SAPT including all 2nd-order terms
sapt2+(3)	SAPT including perturbative triples
sapt2+3
sapt0-ct	0th-order SAPT plus charge transfer (CT) calculation
sapt2-ct	SAPT2 plus CT
sapt2+-ct	SAPT2+ plus CT
sapt2+(3)-ct	SAPT2+(3) plus CT
sapt2+3-ct	SAPT2+3 plus CT
cc2	approximate coupled cluster singles and doubles (CC2)
ccsd	coupled cluster singles and doubles (CCSD)
bccd	Brueckner coupled cluster doubles (BCCD)
cc3	approximate coupled cluster singles, doubles, and triples (CC3)
ccsd(t)	CCSD with perturbative triples
bccd(t)	BCCD with perturbative triples
ccenergy	expert full control over ccenergy module
mpn	nth-order Moller–Plesset perturbation theory
zaptn	nth-order z-averaged perturbation theory (ZAPT)
cisd	configuration interaction (CI) singles and doubles (CISD)
cisdt	CI singles, doubles, and triples (CISDT)
cisdtq	CI singles, doubles, triples, and quadruples (CISDTQ)
cin	nth-order CI
fci	full configuration interaction (FCI)
detci	expert full control over detci module
adc	2nd-order algebraic diagrammatic construction (ADC)
eom-cc2	EOM-CC2
eom-ccsd	equation of motion (EOM) CCSD
eom-cc3	EOM-CC3
cepa(n)	coupled electron pair approximation, variants 0, 1, and 3
acpf	averaged coupled-pair functional
aqcc	averaged quadratic coupled cluster
omp2	orbital-optimized second order Moller–Plesset perturbation theory
scs-omp2	spin-component scaled OMP2
sos-omp2	spin-opposite scaled OMP2
omp3	orbital-optimized third order Moller–Plesset perturbation theory
scs-omp3	spin-component scaled OMP3
sos-omp3	spin-opposite scaled OMP3

name	calls method (aliases to name = ‘scf’)
hf	HF
rhf	HF with restricted reference
uhf	HF with unrestricted reference
rohf	HF with restricted open-shell reference
rscf	HF or DFT with restricted reference
uscf	HF or DFT with unrestricted reference
roscf	HF or DFT with restricted open-shell reference
df-scf	HF or DFT with density fitting

name	calls method
b2plyp	B2PLYP Double Hybrid Exchange-Correlation Functional
b2plyp-d	B2PLYP Double Hybrid Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
b2plyp-d3	B2PLYP Double Hybrid Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
b2plyp-d3bj	B2PLYP Double Hybrid Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
b3lyp	B3LYP Hybrid-GGA Exchange-Correlation Functional
b3lyp-chg	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Chai and Head-Gordon Dispersion Correction
b3lyp-d	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
b3lyp-d1	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D1 Dispersion Correction
b3lyp-d3	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
b3lyp-d3bj	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
b3_x	Becke88 GGA Exchange (B3LYP weighting)
b88_x	Becke88 GGA Exchange
b97-0	B97-0 Hybrid-GGA Exchange-Correlation Functional
b97-1	B97-1 Hybrid-GGA Exchange-Correlation Functional
b97-2	B97-2 Hybrid-GGA Exchange-Correlation Functional
b97-d	B97-D Pure-GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
b97-d3	B97-D Pure-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
b97-d3bj	B97-D Pure-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
blyp	BLYP GGA Exchange-Correlation Functional
blyp-d	BLYP GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
blyp-d1	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D1 Dispersion Correction
blyp-d3	BLYP GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
blyp-d3bj	BLYP GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
bp86	BP86 GGA Exchange-Correlation Functional
bp86-d	BP86 GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
bp86-d1	B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D1 Dispersion Correction
bp86-d3	BP86 GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
bp86-d3bj	BP86 GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
dsd-blyp	DSD-BLYP Dispersion-corrected SCS Double Hybrid XC Functional w/ Grimme’s -D2 Dispersion Correction
dsd-pbep86	DSD-PBEP86 Dispersion-corrected SCS Double Hybrid XC Functional (opt. for -D2) w/ Grimme’s -D2 Dispersion Correction
dsd-pbepbe	DSD-PBEPBE Dispersion-corrected SCS Double Hybrid XC Functional w/ Grimme’s -D2 Dispersion Correction
ft97	FT97 GGA Exchange-Correlation Functional
ft97b_x	Filitov and Theil 1997 Exchange
ft97_c	FT97 Correlation (Involves Ei functions)
hcth	HCTH Pure-GGA Exchange-Correlation Functional
hcth120	HCTH120 Pure-GGA Exchange-Correlation Functional
hcth120-d3	HCTH120 Pure-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
hcth120-d3bj	HCTH120 Pure-GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
hcth147	HCTH147 Pure-GGA Exchange-Correlation Functional
hcth407	HCTH407 Pure-GGA Exchange-Correlation Functional
hf+d	w/ Podeszwa and Szalewicz Dispersion Correction
lyp_c	LYP Correlation
m05	Heavily Parameterized Hybrid Meta-GGA XC Functional
m05-2x	Heavily Parameterized Hybrid Meta-GGA XC Functional
m05-2x-d3	Heavily Parameterized Hybrid Meta-GGA XC Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
m05-d3	Heavily Parameterized Hybrid Meta-GGA XC Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
p86_c	P86 Correlation (PZ81 LSDA + P86 GGA)
pbe	PBE GGA Exchange-Correlation Functional
pbe-d	PBE GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
pbe-d1	PBE GGA Exchange-Correlation Functional w/ Grimme’s -D1 Dispersion Correction
pbe-d3	PBE GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
pbe-d3bj	PBE GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
pbe0	PBE0 Hybrid GGA Exchange-Correlation Functional
pbe0-2	PBE0-2 Double Hydrid Exchange-Correlation Functional
pbe0-d	PBE0 Hybrid GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
pbe0-d3	PBE0 Hybrid GGA Exchange-Correlation Functional w/ Grimme’s -D3 (zero-damping) Dispersion Correction
pbe0-d3bj	PBE0 Hybrid GGA Exchange-Correlation Functional w/ Grimme’s -D3 (BJ-damping) Dispersion Correction
pbesol_x	PBEsol GGA Exchange Hole (Parameter Free)
pbe_c	PBE Correlation
pbe_x	PBE GGA Exchange Hole (Parameter Free)
pw91	PW91 GGA Exchange-Correlation Functional
pw91_c	PW91 Correlation
pw91_x	PW91 Parameterized GGA Exchange
pw92_c
pz81_c	PZ81 Correlation
rpbe_x	RPBE GGA Exchange Hole (Parameter Free)
sogga	Second Order GGA Exchange-Correlation Functional
sogga_x	Second Order GGA Exchange Hole (Parameter Free)
svwn	SVWN3 (RPA) LSDA Functional
s_x	Slater LSDA Exchange
vwn3rpa_c	VWN3 (RPA) LSDA Correlation
vwn3_c	VWN3 LSDA Correlation
vwn5rpa_c	VWN5 (RPA) LSDA Correlation
vwn5_c	VWN5 LSDA Correlation
dldf	Dispersionless Hybrid Meta-GGA XC Functional
dldf+d	Dispersionless Hybrid Meta-GGA XC Functional w/ Podeszwa and Szalewicz Dispersion Correction
dldf+d09	Dispersionless Hybrid Meta-GGA XC Functional w/ Podeszwa and Szalewicz Dispersion Correction
wb88_x	B88 Short-Range GGA Exchange (HJS Model)
wb97	Parameterized LRC B97 GGA XC Functional
wb97x	Parameterized Hybrid LRC B97 GGA XC Functional
wb97x-2(lp)	Double Hybrid LRC B97 GGA XC Functional (Large Pople parametrization)
wb97x-2(tqz)	Double Hybrid LRC B97 GGA XC Functional (TQZ parametrization)
wb97x-d	Parameterized Hybrid LRC B97 GGA XC Functional with Dispersion w/ Chai and Head-Gordon Dispersion Correction
wblyp	BLYP SR-XC Functional (HJS Model)
wpbe	PBE SR-XC Functional (HJS Model)
wpbe0	PBE0 SR-XC Functional (HJS Model)
wpbe_x	PBE Short-Range GGA Exchange (HJS Model)
wpbesol	PBEsol SR-XC Functional (HJS Model)
wpbesol0	PBEsol0 SR-XC Functional (HJS Model)
wpbesol_x	PBEsol Short-Range GGA Exchange (HJS Model)
wsvwn	LSDA SR-XC Functional
ws_x	Slater Short-Range LSDA Exchange

name	calls method in Kallay’s MRCC program
mrccsd	CC through doubles
mrccsdt	CC through triples
mrccsdtq	CC through quadruples
mrccsdtqp	CC through quintuples
mrccsdtqph	CC through sextuples
mrccsd(t)	CC through doubles with perturbative triples
mrccsdt(q)	CC through triples with perturbative quadruples
mrccsdtq(p)	CC through quadruples with pertubative quintuples
mrccsdtqp(h)	CC through quintuples with pertubative sextuples
mrccsd(t)_l
mrccsdt(q)_l
mrccsdtq(p)_l
mrccsdtqp(h)_l
mrccsdt-1a	CC through doubles with iterative triples (cheapest terms)
mrccsdtq-1a	CC through triples with iterative quadruples (cheapest terms)
mrccsdtqp-1a	CC through quadruples with iterative quintuples (cheapest terms)
mrccsdtqph-1a	CC through quintuples with iterative sextuples (cheapest terms)
mrccsdt-1b	CC through doubles with iterative triples (cheaper terms)
mrccsdtq-1b	CC through triples with iterative quadruples (cheaper terms)
mrccsdtqp-1b	CC through quadruples with iterative quintuples (cheaper terms)
mrccsdtqph-1b	CC through quintuples with iterative sextuples (cheaper terms)
mrcc2	approximate CC through doubles
mrcc3	approximate CC through triples
mrcc4	approximate CC through quadruples
mrcc5	approximate CC through quintuples
mrcc6	approximate CC through sextuples
mrccsdt-3	CC through doubles with iterative triples (all but the most expensive terms)
mrccsdtq-3	CC through triples with iterative quadruples (all but the most expensive terms)
mrccsdtqp-3	CC through quadruples with iterative quintuples (all but the most expensive terms)
mrccsdtqph-3	CC through quintuples with iterative sextuples (all but the most expensive terms)

Parameters:

name (string) –
'scf' || 'df-mp2' || 'ci5' || etc.

First argument, usually unlabeled. Indicates the computational method to be applied to the system.
molecule (molecule) –
h2o || etc.

The target molecule, if not the last molecule defined.
cast_up (boolean or string) –
'on' || $\Rightarrow$ 'off' $\Leftarrow$ || '3-21g' || 'cc-pVDZ' || etc.

Indicates whether, to accelerate convergence for the scf portion of the name calculation, a preliminary scf should be performed with a small basis set (3-21G if a basis name is not supplied as keyword value) followed by projection into the full target basis.

Deprecated since version Sept-2012: Use option BASIS_GUESS instead.

Parameters:

cast_up_df (boolean or string) –

'on' || $\Rightarrow$ 'off' $\Leftarrow$ || 'cc-pVDZ-RI' || 'aug-cc-pVDZ-JKFIT' || etc.

Indicates whether, when cast_up is active, to run the preliminary scf in density-fitted mode or what fitting basis to employ (when available for all elements, cc-pVDZ-RI is the default).

Deprecated since version Sept-2012: Use option DF_BASIS_GUESS instead.

Parameters:

bypass_scf (boolean) –

'on' || $\Rightarrow$ 'off' $\Leftarrow$

Indicates whether, for name values built atop of scf calculations, the scf step is skipped. Suitable when special steps are taken to get the scf to converge in an explicit preceeding scf step.

Examples :

>>> # [1] Coupled-cluster singles and doubles calculation with psi code
>>> energy('ccsd')

>>> # [2] Charge-transfer SAPT calculation with scf projection from small into
>>> #     requested basis, with specified projection fitting basis
>>> set basis_guess true
>>> set df_basis_guess jun-cc-pVDZ-JKFIT
>>> energy('sapt0-ct')

>>> # [3] Arbitrary-order MPn calculation
>>> energy('mp4')

>>> # [4] Converge scf as singlet, then run detci as triplet upon singlet reference
>>> molecule H2 {\\n0 1\\nH\\nH 1 0.74\\n}
>>> energy('scf')
>>> H2.set_multiplicity(3)
>>> energy('detci', bypass_scf=True)

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