IAM | PRO | PROMOL

Synopsis

[-]iam|pro|promol  (1||2||5)

Description

This keyword allows to modify the density basis set according to the option value.

Aim

Intended mainly for debugging purposes, its use is related to the option value:

Option
Value		Meaning
1 retain all monopoles with their own populations and discard higher poles: this is an independent atom model which uses the density basis set defined in the IDF (†), provided that em is set to 4.
2 set monopole populations to neutral atom values and discard higher poles: this is a promolecular model which uses the density basis set defined in the IDF (†), provided that em is set to 4.
5 use internally stored spherical atoms: this is a promolecular model which uses the density-basis set computed from Clementi's Hartree-Fock limit atomic wave functions,[1] using a ground-state H atom with standard molecular exponent of 1.24 a.u.[4].
†A VALRAY IDF uses an expansion of either canonical[1] or localized[2] atomic orbitals, eventually modified by kappa-refinement[3]i to describe icore and valence monopole one-electron density functions.

Alternative paths

It's worth noting that a simple way to deal with the promolecular model is to supply PAMoC with an IDF that defines the promolecule of interest directly.

References

  1. "Tables of Atomic Functions"
    Clementi, Enrico
    IBM J. Res. Develop., Suppl. 1965, 9, 2
  2. "Partitioning of Hartree-Fock atomic form factors into core and and valence shells"
    Stewart, R. F.
    In Becker, P., editor, Electron and Magnetization Densities in Molecules and Crystals, pages 427-431. Plenum Press, 1980.
  3. "Shell Population and kappa Refinements with Canonical and Density-Localized Scattering Factors in Analytical Form"
    van der Wal, Rob J.; Stewart, R. F.
    Acta Crystallographica A, 1984, 40, 587-593
  4. "The use of the promolecular charge density to approximate the penetration contribution to intermolecular electrostatic energies"
    Spackman, M. A.
    Chem. Phys. Lett. 2006, 418, 158-162