SAPT

Performs symmetry adapted perturbation theory (SAPT) analysis to quantitatively analyze noncovalent interactions.

General

AIO_CPHF

Do use asynchronous disk I/O in the solution of the CPHF equations? Use may speed up the computation slightly at the cost of spawning an additional thread.

AIO_DF_INTS

Do use asynchronous disk I/O in the formation of the DF integrals? Use may speed up the computation slightly at the cost of spawning an additional thread.

BASIS

Primary basis set, describes the monomer molecular orbitals

  • Type: string
  • Possible Values: basis string
  • Default: No Default

CCD_E_CONVERGENCE

E converge value for CCD

CCD_MAXITER

Max CCD iterations

  • Type: integer
  • Default: 50

CCD_T_CONVERGENCE

Convergence tolerance for CCD amplitudes

DENOMINATOR_ALGORITHM

Denominator algorithm for PT methods. Laplace transformations are slightly more efficient.

  • Type: string
  • Possible Values: LAPLACE, CHOLESKY
  • Default: LAPLACE

DENOMINATOR_DELTA

Maximum error allowed (Max error norm in Delta tensor) in the approximate energy denominators employed for most of the \(E_{disp}^{(20)}\) and \(E_{exch-disp}^{(20)}\) evaluation.

  • Type: double
  • Default: 1.0e-6

DF_BASIS_ELST

Auxiliary basis set for SAPT Elst10 and Exch10 density fitting computations, may be important if heavier elements are involved. Defaults to DF_BASIS_SAPT

  • Type: string
  • Possible Values: basis string
  • Default: No Default

DF_BASIS_SAPT

Auxiliary basis set for SAPT density fitting computations. Defaults to a RI basis.

  • Type: string
  • Possible Values: basis string
  • Default: No Default

D_CONVERGENCE

Convergence criterion for residual of the CPHF coefficients in the SAPT \(E_{ind,resp}^{(20)}\) term.

EXCH_SCALE_ALPHA

Whether or not to perform exchange scaling for SAPT exchange components. Default is false, i.e. no scaling. If set to true, performs scaling with \(Exch10 / Exch10(S^2)\). If set to a value \(\alpha\), performs scaling with \((Exch10 / Exch10(S^2))^{\alpha}\).

  • Type: string
  • Default: FALSE

E_CONVERGENCE

Convergence criterion for energy (change) in the SAPT \(E_{ind,resp}^{(20)}\) term during solution of the CPHF equations.

FREEZE_CORE

The scope of core orbitals to freeze in evaluation of SAPT \(E_{disp}^{(20)}\) and \(E_{exch-disp}^{(20)}\) terms. Recommended true for all SAPT computations

  • Type: string
  • Possible Values: FALSE, TRUE
  • Default: FALSE

INTS_TOLERANCE

Minimum absolute value below which all three-index DF integrals and those contributing to four-index integrals are neglected. The default is conservative, but there isn’t much to be gained from loosening it, especially for higher-order SAPT.

MAXITER

Maximum number of CPHF iterations

  • Type: integer
  • Default: 50

MAX_CCD_DIISVECS

Maximum number of vectors used in CCD-DIIS

  • Type: integer
  • Default: 10

MIN_CCD_DIISVECS

Minimumnumber of vectors used in CCD-DIIS

  • Type: integer
  • Default: 4

NAT_ORBS_T2

Do use MP2 natural orbital approximations for the \(v^4\) block of two-electron integrals in the evaluation of second-order T2 amplitudes? Recommended true for all SAPT computations.

NAT_ORBS_T3

Do natural orbitals to speed up evaluation of the triples contribution to dispersion by truncating the virtual orbital space? Recommended true for all SAPT computations.

NAT_ORBS_V4

Do use MP2 natural orbital approximations for the \(v^4\) block of two-electron integrals in the evaluation of CCD T2 amplitudes? Recommended true for all SAPT computations.

NO_RESPONSE

Don’t solve the CPHF equations? Evaluate \(E_{ind}^{(20)}\) and \(E_{exch-ind}^{(20)}\) instead of their response-including coupterparts. Only turn on this option if the induction energy is not going to be used.

OCC_TOLERANCE

Minimum occupation (eigenvalues of the MP2 OPDM) below which virtual natural orbitals are discarded for in each of the above three truncations

PRINT

The amount of information to print to the output file for the sapt module. For 0, only the header and final results are printed. For 1, (recommended for large calculations) some intermediate quantities are also printed.

  • Type: integer
  • Default: 1

SAPT_LEVEL

The level of theory for SAPT

  • Type: string
  • Possible Values: SAPT0, SAPT2, SAPT2+, SAPT2+3
  • Default: SAPT0

SAPT_MEM_CHECK

Do force SAPT2 and higher to die if it thinks there isn’t enough memory? Turning this off is ill-advised.

SAPT_MEM_SAFETY

Memory safety

  • Type: double
  • Default: 0.9

Expert

COUPLED_INDUCTION

Whether or not to compute coupled induction, applies only to the open-shell SAPT0 code. Coupled induction is not available for ROHF, and the option is automatically false in this case. Note that when coupled induction is turned off, the Psi variables SAPT IND20,R ENERGY and SAPT EXCH-IND20,R ENERGY actually contain the uncoupled induction! A corresponding warning is issued in the output file.

DO_CCD_DISP

Do CCD dispersion correction in SAPT2+, SAPT2+(3) or SAPT2+3?

DO_MBPT_DISP

Do MBPT dispersion correction in SAPT2+, SAPT2+(3) or SAPT2+3, if also doing CCD?

DO_THIRD_ORDER

Do compute third-order corrections?

SAPT0_E10

For SAPT0 only, compute only first-order electrostatics and exchange. The integrals are computed before any terms, so all integrals will be computed even if they are not needed for the requested term

SAPT0_E20DISP

For SAPT0 only, compute only second-order induction The integrals are computed before any terms, so all integrals will be computed even if they are not needed for the requested term

SAPT0_E20IND

For SAPT0 only, compute only second-order induction The integrals are computed before any terms, so all integrals will be computed even if they are not needed for the requested term

SAPT_MEM_FACTOR

Proportion of memory available for the DF-MP2 three-index integral buffers used to evaluate dispersion.

  • Type: double
  • Default: 0.9