Single-Point Energy — energy()

psi4.energy(name[, molecule, return_wfn, restart_file])[source]

Function to compute the single-point electronic energy.

Returns

float – Total electronic energy in Hartrees. SAPT & EFP return interaction energy.

Returns

(float, Wavefunction) – energy and wavefunction when return_wfn specified.

PSI variables

  • CURRENT ENERGY

  • CURRENT REFERENCE ENERGY

  • CURRENT CORRELATION ENERGY

Parameters
  • name (string) –

    'scf' || '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.

  • return_wfn (boolean) –

    'on' || \(\Rightarrow\) 'off' \(\Leftarrow\)

    Indicate to additionally return the Wavefunction calculation result as the second element (after float energy) of a tuple.

  • restart_file (string) –

    ['file.1, file.32] || ./file || etc.

    Binary data files to be renamed for calculation restart.

name

calls method

efp

effective fragment potential (EFP) [manual]

scf

Hartree–Fock (HF) or density functional theory (DFT) [manual]

hf

HF self consistent field (SCF) [manual]

hf3c

HF with dispersion, BSSE, and basis set corrections [manual]

pbeh3c

PBEh with dispersion, BSSE, and basis set corrections [manual]

dct

density cumulant (functional) theory [manual]

mp2

2nd-order Møller–Plesset perturbation theory (MP2) [manual] [details]

mp3

3rd-order Møller–Plesset perturbation theory (MP3) [manual] [details]

fno-mp3

MP3 with frozen natural orbitals [manual]

mp2.5

average of MP2 and MP3 [manual] [details]

mp4(sdq)

4th-order MP perturbation theory (MP4) less triples [manual]

fno-mp4(sdq)

MP4 (less triples) with frozen natural orbitals [manual]

mp4

full MP4 [manual] [details]

fno-mp4

full MP4 with frozen natural orbitals [manual]

mpn

nth-order Møller–Plesset (MP) perturbation theory [manual]

zaptn

nth-order z-averaged perturbation theory (ZAPT) [manual]

omp2

orbital-optimized second-order MP perturbation theory [manual]

scs-omp2

spin-component scaled OMP2 [manual]

scs(n)-omp2

a special version of SCS-OMP2 for nucleobase interactions [manual]

scs-omp2-vdw

a special version of SCS-OMP2 (from ethene dimers) [manual]

sos-omp2

spin-opposite scaled OMP2 [manual]

sos-pi-omp2

A special version of SOS-OMP2 for pi systems [manual]

omp3

orbital-optimized third-order MP perturbation theory [manual]

scs-omp3

spin-component scaled OMP3 [manual]

scs(n)-omp3

a special version of SCS-OMP3 for nucleobase interactions [manual]

scs-omp3-vdw

a special version of SCS-OMP3 (from ethene dimers) [manual]

sos-omp3

spin-opposite scaled OMP3 [manual]

sos-pi-omp3

A special version of SOS-OMP3 for pi systems [manual]

omp2.5

orbital-optimized MP2.5 [manual]

lccsd, cepa(0)

coupled electron pair approximation variant 0 [manual] [details]

fno-lccsd, fno-cepa(0)

CEPA(0) with frozen natural orbitals [manual]

cepa(1)

coupled electron pair approximation variant 1 [manual]

fno-cepa(1)

CEPA(1) with frozen natural orbitals [manual]

cepa(3)

coupled electron pair approximation variant 3 [manual]

fno-cepa(3)

CEPA(3) with frozen natural orbitals [manual]

acpf

averaged coupled-pair functional [manual]

fno-acpf

ACPF with frozen natural orbitals [manual]

aqcc

averaged quadratic coupled cluster [manual]

fno-aqcc

AQCC with frozen natural orbitals [manual]

qcisd

quadratic CI singles doubles (QCISD) [manual]

fno-qcisd

QCISD with frozen natural orbitals [manual]

lccd

Linear CCD [manual] [details]

fno-lccd

LCCD with frozen natural orbitals [manual]

olccd

orbital optimized LCCD [manual]

cc2

approximate coupled cluster singles and doubles (CC2) [manual]

ccd

coupled cluster doubles (CCD) [manual]

ccsd

coupled cluster singles and doubles (CCSD) [manual] [details]

bccd

Brueckner coupled cluster doubles (BCCD) [manual]

fno-ccsd

CCSD with frozen natural orbitals [manual]

qcisd(t)

QCISD with perturbative triples [manual]

fno-qcisd(t)

QCISD(T) with frozen natural orbitals [manual]

ccsd(t)

CCSD with perturbative triples (CCSD(T)) [manual] [details]

ccsd(at)

CCSD with asymmetric perturbative triples (CCSD(AT)) [manual] [details]

bccd(t)

BCCD with perturbative triples [manual]

fno-ccsd(t)

CCSD(T) with frozen natural orbitals [manual]

cc3

approximate CC singles, doubles, and triples (CC3) [manual]

ccenergy

expert full control over ccenergy module

dfocc

expert full control over dfocc module

cisd

configuration interaction (CI) singles and doubles (CISD) [manual] [details]

fno-cisd

CISD with frozen natural orbitals [manual]

cisdt

CI singles, doubles, and triples (CISDT) [manual]

cisdtq

CI singles, doubles, triples, and quadruples (CISDTQ) [manual]

cin

nth-order CI [manual]

fci

full configuration interaction (FCI) [manual]

detci

expert full control over detci module

casscf

complete active space self consistent field (CASSCF) [manual]

rasscf

restricted active space self consistent field (RASSCF) [manual]

mcscf

multiconfigurational self consistent field (SCF) [manual]

psimrcc

Mukherjee multireference coupled cluster (Mk-MRCC) [manual]

dmrg-scf

density matrix renormalization group SCF [manual]

dmrg-caspt2

density matrix renormalization group CASPT2 [manual]

dmrg-ci

density matrix renormalization group CI [manual]

sapt0

0th-order symmetry adapted perturbation theory (SAPT) [manual]

ssapt0

0th-order SAPT with special exchange scaling [manual]

fisapt0

0th-order functional and/or intramolecular SAPT [manual]

sapt2

2nd-order SAPT, traditional definition [manual]

sapt2+

SAPT including all 2nd-order terms [manual]

sapt2+(3)

SAPT including perturbative triples [manual]

sapt2+3

SAPT including all 3rd-order terms [manual]

sapt2+(ccd)

SAPT2+ with CC-based dispersion [manual]

sapt2+(3)(ccd)

SAPT2+(3) with CC-based dispersion [manual]

sapt2+3(ccd)

SAPT2+3 with CC-based dispersion [manual]

sapt2+dmp2

SAPT including all 2nd-order terms and MP2 correction [manual]

sapt2+(3)dmp2

SAPT including perturbative triples and MP2 correction [manual]

sapt2+3dmp2

SAPT including all 3rd-order terms and MP2 correction [manual]

sapt2+(ccd)dmp2

SAPT2+ with CC-based dispersion and MP2 correction [manual]

sapt2+(3)(ccd)dmp2

SAPT2+(3) with CC-based dispersion and MP2 correction [manual]

sapt2+3(ccd)dmp2

SAPT2+3 with CC-based dispersion and MP2 correction [manual]

sapt0-ct

0th-order SAPT plus charge transfer (CT) calculation [manual]

sapt2-ct

SAPT2 plus CT [manual]

sapt2+-ct

SAPT2+ plus CT [manual]

sapt2+(3)-ct

SAPT2+(3) plus CT [manual]

sapt2+3-ct

SAPT2+3 plus CT [manual]

sapt2+(ccd)-ct

SAPT2+(CCD) plus CT [manual]

sapt2+(3)(ccd)-ct

SAPT2+(3)(CCD) plus CT [manual]

sapt2+3(ccd)-ct

SAPT2+3(CCD) plus CT [manual]

adc

2nd-order algebraic diagrammatic construction (ADC) [manual]

eom-cc2

EOM-CC2 [manual]

eom-ccsd

equation of motion (EOM) CCSD [manual]

eom-cc3

EOM-CC3 [manual]

name

calls method DFT [manual]

b1lyp

B1LYP Hyb-GGA Exchange-Correlation Functional

b1lyp-d3bj

b1pw91

B1PW91 Hyb-GGA Exchange-Correlation Functional

b1wc

B1WC Hyb-GGA Exchange-Correlation Functional

b2gpplyp

B2GPPLYP Double Hybrid Exchange-Correlation Functional

b2gpplyp-d3bj

b2gpplyp-nl

B2GPPLYP Double Hybrid Exchange-Correlation Functional

b2plyp

B2PLYP Double Hybrid Exchange-Correlation Functional

b2plyp-d3bj

b2plyp-d3mbj

b2plyp-nl

B2PLYP Double Hybrid Exchange-Correlation Functional

b3lyp

B3LYP Hyb-GGA Exchange-Correlation Functional

b3lyp-d3bj

b3lyp-d3mbj

b3lyp-nl

B3LYP-nl Hyb-GGA Exchange-Correlation Functional

b3lyp5

B3LYP5 Hyb-GGA Exchange-Correlation Functional

b3lyps

B3LYPs Hyb-GGA Exchange-Correlation Functional

b3p86

B3P86 Hyb-GGA Exchange-Correlation Functional

b3p86-d3bj

b3pw91

B3PW91 Hyb-GGA Exchange-Correlation Functional

b3pw91-d3bj

b3pw91-nl

B3PW91-nl Hyb-GGA Exchange-Correlation Functional

b5050lyp

B5050LYP Hyb-GGA Exchange-Correlation Functional

b86b95

B86B95 Hyb-GGA Exchange-Correlation Functional

b86bpbe

B86BPBE GGA Exchange-Correlation Functional

b88b95

B88B95 Hyb-GGA Exchange-Correlation Functional

b88b95-d3bj

b97-0

B97-0 Hyb-GGA Exchange-Correlation Functional

b97-1

B97-1 Hyb-GGA Exchange-Correlation Functional

b97-1-d3bj

b97-1p

B97-1p Hyb-GGA Exchange-Correlation Functional

b97-2

B97-2 Hyb-GGA Exchange-Correlation Functional

b97-2-d3bj

b97-3

B97-3 Hyb-GGA Exchange-Correlation Functional

b97-d

b97-d3bj

b97-d3mbj

b97-gga1

B97-GGA1 GGA Exchange-Correlation Functional

b97-k

B97-K Hyb-GGA Exchange-Correlation Functional

b97m-d3bj

b97m-v

B97M-V GGA Exchange-Correlation Functional

bb1k

BB1K Hyb-GGA Exchange-Correlation Functional

bhandh

BHandH Hyb-GGA Exchange-Correlation Functional

bhandhlyp

BHandHLYP Hyb-GGA Exchange-Correlation Functional

blyp

BLYP GGA Exchange-Correlation Functional

blyp-d3bj

blyp-d3mbj

blyp-nl

BLYP GGA Exchange-Correlation Functional

bmk

BMK Hybrid Meta-GGA XC Functional for kinetics

bmk-d3bj

bop

BOP GGA Exchange-Correlation Functional

bop-d3bj

bp86

BP86 GGA Exchange-Correlation Functional

bp86-d3bj

bp86-d3mbj

bp86-nl

BP86 GGA Exchange-Correlation Functional

bp86-vwn

BP86 GGA XC Functional based on VWN5 corr. & more accurate ftilde value

cam-b3lyp

CAM-B3LYP Hyb-GGA Exchange-Correlation Functional

cam-b3lyp-d3bj

cam-lda0

CAM-LDA0 Exchange-Correlation Functional

cap0

CAP0 Hyb-GGA Exchange-Correlation Functional

core-dsd-blyp

core-dsd-blyp-d3bj

dldf

Dispersionless Hybrid Meta-GGA XC Functional

dldf+d09

Dispersionless Hybrid Meta-GGA XC Functional

dldf+d10

Dispersionless Hybrid Meta-GGA XC Functional

dsd-blyp

DSD-BLYP SCS Double Hybrid XC Functional (not dispersion corrected)

dsd-blyp-d3bj

dsd-blyp-nl

DSD-BLYP-NL (D3BJ,FC parameters) VV10 SCS Double Hybrid XC Functional

dsd-pbeb95

DSD-PBEB95 SCS Double Hybrid Meta-GGA XC Functional (not dispersion corrected)

dsd-pbeb95-d3bj

dsd-pbeb95-nl

DSD-PBEB95-NL (D3BJ parameters) VV10 SCS Double Hybrid Meta-GGA XC Functional

dsd-pbep86

DSD-PBEP86 SCS Double Hybrid XC Functional (not dispersion corrected)

dsd-pbep86-d3bj

dsd-pbep86-nl

DSD-PBEP86-NL (D3BJ parameters) VV10 SCS Double Hybrid XC Functional

dsd-pbepbe

DSD-PBEPBE SCS Double Hybrid XC Functional (not dispersion corrected)

dsd-pbepbe-d3bj

dsd-pbepbe-nl

DSD-PBEPBE-NL (D3BJ parameters) VV10 SCS Double Hybrid XC Functional

edf1

EDF1 GGA Exchange-Correlation Functional

edf2

EDF2 Hyb-GGA Exchange-Correlation Functional

ft97

FT97 GGA Exchange-Correlation Functional

gam

GAM GGA Minessota Exchange-Correlation Functional

hcth120

HCTH120 GGA Exchange-Correlation Functional

hcth120-d3bj

hcth147

HCTH147 GGA Exchange-Correlation Functional

hcth407

HCTH407 GGA Exchange-Correlation Functional

hcth407-d3bj

hcth407p

HCTH407P GGA Exchange-Correlation Functional

hcth93

HCTH93 GGA Exchange-Correlation Functional

hcthp14

HCTHP14 GGA Exchange-Correlation Functional

hcthp76

HCTHP76 GGA Exchange-Correlation Functional

hf

hf+d

hf-d3bj

hf-d3mbj

hf-nl

hf3c

Hartree Fock based 3C composite method with minimal basis set, gCP and D3(BJ)

hjs-b88

HJS-B88 Hyb-GGA Exchange-Correlation Functional

hjs-b97x

HJS-B97X Hyb-GGA Exchange-Correlation Functional

hjs-pbe

HJS-PBE Hyb-GGA Exchange-Correlation Functional

hjs-pbe-sol

HJS-PBE-SOL Hyb-GGA Exchange-Correlation Functional

hpbeint

HPBEINT Hyb-GGA Exchange-Correlation Functional

hse03

HSE03 Hyb-GGA Exchange-Correlation Functional

hse03-d3bj

hse06

HSE06 Hyb-GGA Exchange-Correlation Functional

hse06-d3bj

ksdt

KSDT Exchange-Correlation Functional

kt2

KT2 GGA Exchange-Correlation Functional

lc-bop

LC-BOP GGA Exchange-Correlation Functional

lc-vv10

LC-VV10 GGA Exchange-Correlation Functional

lda0

LDA0 Exchange-Correlation Functional

lrc-wpbe

LRC-WPBE GGA Exchange-Correlation Functional

lrc-wpbeh

LRC-wPBEh Hyb-GGA Exchange-Correlation Functional

m05

M05 Meta-GGA XC Functional

m05-2x

Heavily Parameterized Hybrid M05-2X Meta-GGA XC Functional

m06

M06 Meta-GGA XC Functional

m06-2x

Hybrid M06-2X Meta-GGA XC Functional

m06-hf

Minnesota M06-HF Hybrid XC Functional

m06-l

M06-L Meta-GGA XC Functional

m08-hx

Minnesota M08-HX Hybrid XC Functional

m08-so

Minnesota M08-SO Hybrid XC Functional

m11

M11 Meta-GGA XC Functional

m11-d3bj

m11-l

M11-L Meta-GGA XC Functional

m11-l-d3bj

mb3lyp-rc04

MB3LYP-RC04 Hyb-GGA Exchange-Correlation Functional

mgga_ms0

MGGA_MS0 Meta-GGA XC Functional

mgga_ms1

MGGA_MS1 Meta-GGA XC Functional

mgga_ms2

MGGA_MS2 Meta-GGA XC Functional

mgga_ms2h

MGGA_MS2h Hybrid Meta-GGA XC Functional

mgga_mvs

MGGA_MVS Meta-GGA XC Functional

mgga_mvsh

MGGA_MV2h Hybrid Meta-GGA XC Functional

mn12-l

MN12-L Meta-GGA XC Functional

mn12-l-d3bj

mn12-sx

MN12-SX Meta-GGA Hybrid Screened Exchange-Correlation Functional

mn12-sx-d3bj

mn15

MN15 Hybrid Meta-GGA Exchange-Correlation Functional

mn15-d3bj

mn15-l

MN15-L Meta-GGA XC Functional

mohlyp

MOHLYP GGA Exchange-Correlation Functional

mohlyp2

MOHLYP2 GGA Exchange-Correlation Functional

mp2d

mp2mp2

mpw1b95

mPW1B95 Hyb-GGA Exchange-Correlation Functional

mpw1b95-d3bj

mpw1k

mPW1K Hyb-GGA Exchange-Correlation Functional

mpw1lyp

mPW1LYP Hybrid GGA Exchange-Correlation Functional

mpw1pbe

mPW1PBE Hybrid GGA Exchange-Correlation Functional

mpw1pw

mPW1PW Hyb-GGA Exchange-Correlation Functional

mpw1pw-d3bj

mpw3lyp

mPW3LYP Hyb-GGA Exchange-Correlation Functional

mpw3pw

mPW3PW Hyb-GGA Exchange-Correlation Functional

mpwb1k

mPWB1K Hyb-GGA Exchange-Correlation Functional

mpwb1k-d3bj

mpwlyp1m

mPWLYP1M Hyb-GGA Exchange-Correlation Functional

mpwlyp1w

mPWLYP1W GGA Exchange-Correlation Functional

mpwpw

mPWPW GGA Exchange-Correlation Functional

n12

N12 nonseparable GGA Exchange-Correlation Functional

n12-d3bj

n12-sx

N12-SX Hybrid nonseparable GGA Exchange-Correlation Functional

n12-sx-d3bj

o3lyp

O3LYP Hyb-GGA Exchange-Correlation Functional

o3lyp-d3bj

oblyp-d

op-pbe

BP86 GGA Exchange-Correlation Functional

opbe-d

opwlyp-d

otpss-d

pbe

PBE GGA Exchange-Correlation Functional

pbe-d3bj

pbe-d3mbj

pbe-nl

PBE GGA Exchange-Correlation Functional

pbe-sol

Perdew, Burke & Ernzerhof exchange (solids)

pbe-sol-d3bj

pbe0

PBE0 Hyb-GGA Exchange-Correlation Functional

pbe0-13

PBE0-13 Hyb-GGA Exchange-Correlation Functional

pbe0-2

PBE0-2 Double Hybrid Exchange-Correlation Functional

pbe0-d3bj

pbe0-d3mbj

pbe0-dh

pbe0-dh-d3bj

pbe0-nl

PBE0-nl Hyb-GGA Exchange-Correlation Functional

pbe1w

PBE1W GGA Exchange-Correlation Functional

pbe50

PBE50 Hybrid GGA Exchange-Correlation Functional

pbeh3c

PBE Hybrid based 3C composite method with a small basis set, gCP and D3(BJ)

pbelyp1w

PBELYP1W GGA Exchange-Correlation Functional

pkzb

PKZB Meta-GGA XC Functional

ptpss

PTPSS SOS Double Hybrid XC Functional

ptpss-d3bj

pw6b95

PW6B95 Hybrid Meta-GGA XC Functional

pw6b95-d3bj

pw86b95

PW86B95 Hyb-GGA Exchange-Correlation Functional

pw86pbe

PW86PBE GGA Exchange-Correlation Functional

pw91

PW91 GGA Exchange-Correlation Functional

pw91-d3bj

pwb6k

PWB6K Hyb-GGA Exchange-Correlation Functional

pwb6k-d3bj

pwpb95

PWPB95 SOS Double Hybrid XC Functional

pwpb95-d3bj

pwpb95-nl

PWPB95 SOS Double Hybrid XC Functional

revb3lyp

revB3LYP Hyb-GGA Exchange-Correlation Functional

revm06-l

Revised M06-L Meta-GGA XC Functional

revpbe

revPBE GGA Exchange-Correlation Functional

revpbe-d3bj

revpbe-nl

revPBE GGA Exchange-Correlation Functional

revpbe0

revPBE0 Hybrid GGA Exchange-Correlation Functional

revpbe0-d3bj

revpbe0-nl

revPBE0 Hybrid GGA Exchange-Correlation Functional

revscan

Revised SCAN Meta-GGA XC Functional

revscan0

Revised SCAN0 Hybrid Meta-GGA XC Functional

revtpss

revised TPSS Meta-GGA XC Functional

revtpss-d3bj

revtpss-nl

revised TPSS Meta-GGA XC Functional

revtpssh

revTPSSh Hyb-GGA Exchange-Correlation Functional

revtpssh-d3bj

rpbe

RPBE GGA Exchange-Correlation Functional

rpbe-d3bj

sb98-1a

SB98-1a Hyb-GGA Exchange-Correlation Functional

sb98-1b

SB98-1b Hyb-GGA Exchange-Correlation Functional

sb98-1c

SB98-1c Hyb-GGA Exchange-Correlation Functional

sb98-2a

SB98-2a Hyb-GGA Exchange-Correlation Functional

sb98-2b

SB98-2b Hyb-GGA Exchange-Correlation Functional

sb98-2c

SB98-2c Hyb-GGA Exchange-Correlation Functional

scan

SCAN Meta-GGA XC Functional

scan-d3bj

scan0

SCAN0 Hybrid Meta-GGA XC Functional

sogga

SOGGA Exchange + PBE Correlation Functional

sogga11

SOGGA11 Exchange-Correlation Functional

sogga11-x

SOGGA11-X Hybrid Exchange-Correlation Functional

sogga11-x-d3bj

svwn

SVWN3 (RPA) LSDA Functional

t-hcth

Tau HCTH Meta-GGA XC Functional

t-hcth-d3bj

t-hcthh

Hybrid Tau HCTH Meta-GGA XC Functional

teter93

TETER93 Exchange-Correlation Functional

th-fc

TH-FC GGA Exchange-Correlation Functional

th-fcfo

TH-FCFO GGA Exchange-Correlation Functional

th-fco

TH-FCO GGA Exchange-Correlation Functional

th-fl

TH-FL GGA Exchange-Correlation Functional

th1

TH1 GGA Exchange-Correlation Functional

th2

TH2 GGA Exchange-Correlation Functional

th3

TH3 GGA Exchange-Correlation Functional

th4

TH4 GGA Exchange-Correlation Functional

tpss

TPSS Meta-GGA XC Functional

tpss-d3bj

tpss-nl

TPSS Meta-GGA XC Functional

tpssh

TPSSh Hyb-GGA Exchange-Correlation Functional

tpssh-d3bj

tpssh-nl

TPSSh-nl Hyb-GGA Exchange-Correlation Functional

tpsslyp1w

TPSSLYP1W GGA Exchange-Correlation Functional

tuned-cam-b3lyp

TUNED-CAM-B3LYP Hyb-GGA Exchange-Correlation Functional

vsxc

VSXC Meta-GGA XC Functional

vv10

VV10 GGA Exchange-Correlation Functional

wb97

wB97 GGA Exchange-Correlation Functional

wb97m-d3bj

wb97m-v

wB97M-V Hyb-GGA Exchange-Correlation Functional

wb97x

wB97X Hyb-GGA Exchange-Correlation Functional

wb97x-d

wb97x-d3bj

wb97x-v

wB97X-V Hyb-GGA Exchange-Correlation Functional

wpbe

PBE SR-XC Functional (HJS Model)

wpbe-d3bj

wpbe-d3mbj

wpbe0

PBE0 SR-XC Functional (HJS Model)

x1b95

X1B95 Hyb-GGA Exchange-Correlation Functional

x3lyp

X3LYP Hyb-GGA Exchange-Correlation Functional

x3lyp-d3bj

xb1k

XB1K Hyb-GGA Exchange-Correlation Functional

xlyp

XLYP GGA Exchange-Correlation Functional

xlyp-d3bj

zlp

ZLP GGA Exchange-Correlation Functional

name

calls method in Kallay’s MRCC program [manual]

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)

name

calls method in Stanton and Gauss’s CFOUR program [manual]

c4-scf

Hartree–Fock (HF)

c4-mp2

2nd-order Møller–Plesset perturbation theory (non-density-fitting) (MP2)

c4-mp3

3rd-order Møller–Plesset perturbation theory (MP3)

c4-mp4(sdq)

4th-order MP perturbation theory (MP4) less triples

c4-mp4

full MP4

c4-cc2

approximate coupled cluster singles and doubles (CC2)

c4-ccsd

coupled cluster singles and doubles (CCSD)

c4-cc3

approximate CC singles, doubles, and triples (CC3)

c4-ccsd(t)

CCSD with perturbative triples (CCSD(T))

c4-ccsdt

coupled cluster singles, doubles, and triples (CCSDT)

cfour

expert full control over cfour program

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('mp7')
>>> # [4] Converge scf as singlet, then run detci as triplet upon singlet reference
>>> # Note that the integral transformation is not done automatically when detci is run in a separate step.
>>> molecule H2 {\n0 1\nH\nH 1 0.74\n}
>>> set basis cc-pVDZ
>>> set reference rohf
>>> scf_e, scf_wfn = energy('scf', return_wfn=True)
>>> H2.set_multiplicity(3)
>>> core.MintsHelper(scf_wfn.basisset()).integrals()
>>> energy('detci', ref_wfn=scf_wfn)
>>> # [5] Run two CI calculations, keeping the integrals generated in the first one.
>>> molecule ne {\nNe\n}
>>> set basis cc-pVDZ
>>> cisd_e, cisd_wfn = energy('cisd', return_wfn=True)
>>> energy('fci', ref_wfn=cisd_wfn)
>>> # [6] Can automatically perform complete basis set extrapolations
>>> energy("CCSD/cc-pV[DT]Z")
>>> # [7] Can automatically perform delta corrections that include extrapolations
>>> # even with a user-defined extrapolation formula. See sample inputs named
>>> # cbs-xtpl* for more examples of this input style
>>> energy("MP2/aug-cc-pv([d,t]+d)z + d:ccsd(t)/cc-pvdz", corl_scheme=myxtplfn_2)