SAPT Programs

The main program required for SAPT calculations is the SAPT2016 suite. SAPT can use several integral/SCF programs as the front end. One of these codes, ATMOL, can be also downloaded from our site (see below). Other free molecular structure programs that have been extensively tested with SAPT are DALTON and GAMESS. SAPT2016 user manual is available in the documentation section. Short installation instructions extracted from the documentation are also available.

SAPT2016 contains SAPT(DFT), i.e., SAPT based on the Kohn-Sham description of monomers and including the dispersion energies from time-dependent density functional calculations described in A. J. Misquitta, R. Podeszwa, B. Jeziorski, and K. Szalewicz, J. Chem. Phys., 123, 214103 (2005). SAPT(DFT) requires DALTON, as the DFT front-end. DALTON is an advanced quantum chemistry package, available free of change (see the website for instruction how to obtain the program). SAPT(DFT) is faster than the regular SAPT at a comparable accuracy, however, this version is still limited by the regular SAPT transformation. However, a faster code utilizing density fitting [R. Podeszwa, R. Bukowski, and K. Szalewicz, J. Chem. Theory Comput., 2, 400–412 (2006)] is now included in SAPT2016.

Open-shell SAPT(DFT) is also available in the current version. It contains a special version of the SAPT codes for open-shell high-spin complexes [P. S. Żuchowski, R. Podeszwa, R. Moszyński, B. Jeziorski, and K. Szalewicz, “Symmetry-adapted perturbation theory utilizing density functional description of monomers for high-spin open-shell complexes”, J. Chem. Phys. 129, 084101 (2008).]

Separate set of codes for calculating 3-body SAPT corrections for trimers is also available for download. The theory is described in V. F. Lotrich and K. Szalewicz “Symmetry-Adapted Perturbation Theory of Three-Body Nonadditivity of Intermolecular Interaction Energy”, J. Chem. Phys. 106, 9668 (1997) and V. F. Lotrich and K. Szalewicz “Perturbation Theory of Three-Body Exchange Nonadditivity and Application to Helium Trimer”, J. Chem. Phys. 112, 112 (2000). The package also incudes three-body SAPT(DFT) code [R. Podeszwa and K. Szalewicz, J. Chem. Phys 126, 194101 (2007)].

The "alpha" version of the parallel SAPT code, psapt2K2 is also available, with essentially the same functionality as that of the former version SAPT2002. The parallel version has been tested with GAMESS(US) as the SCF front-end program on the SGI, SP3, and SP4 parallel platforms as well as on a Beowulf cluster with distributed memory and disk space running the Linux operating system. All modules of psapt2K2 have been parallelized using only MPI and thus the suite is easily portable. It is also recommended (although not necessary) that the SCALAPACK/BLACS libraries are installed. A chapter about installation and usage of psapt2K2 is included in the SAPT2012 User Guide.

The autoPES package is a separate set of programs and scripts for automatic generation of intermolecular potential energy surfaces. The autoPES package is dependent on SAPT2016 to run, and includes its own, separate documentation. For a description of the methodology implemented in autoPES, see [M. P. Metz, K. Piszczatowski, and K. Szalewicz, J. Chem. Theory Comput. (2016)]

ATMOL is a SCF/integral calculation program This code has been created by Vic Saunders and Martin Guest. Any use of ATMOL should be cited in publications in the form:

V.R. Saunders and M.F. Guest
ATMOL Program Package
(SERC Daresbury Laboratory, Daresbury, Great Britain).

No separate license is needed to download ATMOL, however, the users are asked to write a courtesy email to Vic Saunders ( informing him about intended use.

A typical goal of theoretical work on intermolecular potentials is to obtain a fit to ab initio computed points. An important feature of the SAPT approach is that it is asymptotically compatible with the multipole expansion of the interaction energy in the form Cn /R n where Cn are the van der Waals constants. These constants can be computed from monomer properties and then used as fixed parameters in the fit containing in addition to the damped asymptotic terms also exponential terms: in this way the long-rang part of the potential can be reproduced very faithfully. A set of programs have been written at the University of Delaware which perform such fits and these programs are available for download. The asymptotic constants are computed using a set of programs written by Paul Wormer and Hinne Hettema. Any use of the latter programs should be cited in publications in the form:

P.E.S. Wormer and H. Hettema,
POLCOR package,
University of Nijmegen, The Netherlands, 1992.