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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
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
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
b3lyp B3LYP Hybrid-GGA Exchange-Correlation Functional
b3lyp-d B3LYP Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
b3lyp5 B3LYP5 Hybrid-GGA Exchange-Correlation Functional
b3lyp5-d B3LYP5 Hybrid-GGA Exchange-Correlation Functional w/ Grimme’s -D2 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
blyp BLYP GGA Exchange-Correlation Functional
blyp-d BLYP GGA Exchange-Correlation Functional w/ Grimme’s -D2 Dispersion Correction
bp86 BP86 GGA Exchange-Correlation Functional
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
hcth147 HCTH147 Pure-GGA Exchange-Correlation Functional
hcth407 HCTH407 Pure-GGA Exchange-Correlation Functional
lyp_c LYP Correlation
m05 Heavily Parameterized Hybrid Meta-GGA XC Functional
m05-2x Heavily Parameterized Hybrid Meta-GGA XC Functional
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
pbe0 PBE0 Hybrid GGA Exchange-Correlation Functional
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
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
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-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.

  • 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
>>> energy('sapt0-ct',cast_up=True)
>>> # [3] Arbitrary-order MPn calculation
>>> energy('mp4')

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