Single-Point Energy — energy()

• Psi4 Native Energy Methods

• Psi4 Native DFT Energy Methods

• MRCC Interfaced Energy Methods

• CFOUR Interfaced Energy Methods

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

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)