37.8 Options

`SAPT_LEVEL`- Set to 1 for first-order terms ( and ), to 2 for additional second order (exchange-)induction terms ( and ) and 3 for all first- and second-order terms (including then also and ) (default 3)
`SAPT_FITLEVEL`- Level of density fitting approximations in SAPT which can have values 0 to 3 (default 0)
`SAPT_ICPKS`- Switch between iterative (=1) and non-iterative (=0) solution of coupled-perturbed Kohn-Sham equations (default 0)
`SAPT_CPKSTHR`- Threshold for density matrix convergency in the coupled-perturbed Kohn-Sham program (default 1.d-6).
`SAPT_CPKMAXIT`- Maximum number of iterations in the coupled-perturbed Kohn-Sham program (default 50).
`SAPT_FROZENA`- Number of frozen electrons in the response calculations for monomer A (default 0)

The following parameters are of importance if `SAPT_FITLEVEL`

0:

`SAPT_NFRQ_DISP`- Number of frequencies for the Casimir-Polder integration (default 12)
`SAPT_NORM_DISP`- Norm for the density fitting
which can be either
`COULOMB`or`NATURAL`(default`COULOMB`) `SAPT_DISP_N4`- Can speedup the calculation of the dispersion energy by scaling (default 1)
`THR_XCKERN`- Density threshold for the xc kernel matrix elements (default 1.d-8)
`FIT_XCKERN`- Fit both sides of the xc kernel (default 0)
`SAPT_DISK`- If 0 write all dimer amplitudes to file, if 1 write 3-index response propagators to file and if 2 write 3-index response propagators compressed to file. The latter two variants save disk space but need more CPU time to compute (default 0)
`COMPRESS_THR`- If
`SAPT_DISK`=2 this value determines the compression cutoff (default 1d-12) `UNCOUPLED`- If
`SAPT_DISK`0 calculate also uncoupled (exchange-)dispersion energies (default false) `THRAO`- Threshold for AO 3-index integrals (default 1.d-12)
`THRMO`- Threshold for MO 3-index integrals (default 1.d-8)
`THROV`- Threshold for AO 2-index integrals (default 1.d-10)
`THRPROD`- Product threshold for first half transformation (default 1.d-8)
`THRSW`- Threshold for Schwarz screening (default 1.d-5)
`C6`- Calculate dispersion coefficients for the two monomers (Note that the full dimer basis set is used in each case and that a closer distance of the monomers can perturb the result).
`XCKERN_NBLOCK`- number of grid points treated together as a block for (auxfoccvirt) integrals (default 128)
`CFAC`- factor for VWN correlation in ALDA xc-kernel (default 1.d0)

The last threshold values for the 2- and 3-index integrals should not be set higher in density fitting calculations as this can cause lower accuracies in the interaction terms. In addition SAPT knows the following subcommands:

`MONOMERA`- Stores informations (like number of electrons, etc.) about previous monomer A calculation
`MONOMERB`- See above
`INTERMOL`- Starts the SAPT calculation

`INTERMOL` may have the following subkeywords:

`CA`- Record number of wave function for monomer A (always needed)
`CB`- Record number of wave function for monomer B (always needed)
`SAPTLEVEL`- See above
`FITLEVEL`- See above
`ICPKS`- See above
`FROZA`- See above
`FROZB`- See above
`NLEXFAC`- Amount of nonlocal exact exchange in hybrid DFT-SAPT calculations
`CPKSTHR`- Threshold for density matrix convergency in the coupled-perturbed Kohn-Sham program.
`CPKSMAXIT`- Maximum number of iterations in the coupled-perturbed Kohn-Sham program.

molpro@molpro.net 2019-03-18