ARP | RAP | REPAR

[-]arp|rap|repar   1|2|3|4|5

This keyword allows to specify which set of Repulsion Atomic Parameters has to be used for calculation of atom-atom exchange-repulsion interaction energies.

The following sets are available:

1. Original Spackman's Atomic Parameters, SAP's (Spackman, 1986)
2. Scaled SAP's to fit Ziegler-Rauk ADF-BLYP/TZP repulsion energies.
3. Least-squares refined AP's, which fit Ziegler-Rauk ADF-BLYP/TZP repulsion energies. Available for H, C, N, O and S. For the remaining atoms, option 2 is adopted.
4. Scaled SAP's to fit Kitaura-Morokuma GAMESS-HF/6-31G(d) repulsion energies.
5. Least-squares refined AP's, which fit Kitaura-Morokuma GAMESS-HF/6-31G(d) repulsion energies. Available for H, C, N and O. For atom S the value of option 3 is adopted. For the remaining atoms, option 4 is adopted.

Option 5 is the default.

Calculation of exchange-repulsion interaction energies, using a Born-Mayer potential.

1. "Atom-atom potentials via electron gas theory"
   Mark A. Spackman
   J. Chem. Phys. 1986, 85, 6579-6586.