# energy

`psi4.driver.``energy`(name, **kwargs)

  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]
  dcft | 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
  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
  cam-b3lyp | CAM-B3LYP Hyb-GGA Exchange-Correlation Functional
  cam-b3lyp-d3bj |
  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-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-vv10 | LC-VV10 GGA 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
  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
  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-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
  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
  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
  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
  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)