Program GenGrid

This program reads in the geometry and wave function files and generates an appropriate radial grid.

Input data records

  1. iUGeom, iUOrb, iUGrd
  2. RMax
  3. HFacGauss, HFacWave
  4. EMax
  5. If iUOrb = 0 then read:
    XMaxAlpha(1)

Definition of the input variables

iUGeom
input unit with geometry information.
iUorb
input unit with orbital basis set and expansion coefficients information. If this file present (i. e. iUorb > 0) then the molecular basis set is used to determine how tight the grid needs to be in the regions near the nuclei.
iUGrid
output unit with the computed grid.
RMax
a real number specifing the maximum value of r (in atomic units) in the radial grid.
HFacGauss
factor used to control the step size relative to a Gaussian function in the region of a nucleus. A good default value is 30.0.
HFacWave
factor used to control the step size relative to wave vector k in the asymptotic part of the grid. A good default value is 120.0.
EMax
a real number specifing the maximum value of the electron kinetic energy (in eV) to be computed. This is used to control the step size in the asymptotic part of the radial grid.
XMaxAlpha(1)
a real number which specifies a Gaussian exponent for the origin in the absence of information about the molecular basis set (i. e. iUOrb = 0).

In regions controlled by Gaussians, the step size is determined by

h = max(x/HFacGauss, sqrt(0.1/alphax)/HFacGauss)

where x is the distance to the center containing the Gaussians and alphax is the maximum gaussian exponent at that center.

In regions controlled by the wave length, the step size is given by

h = pi/(HFacWave*KLocal)

where KLocal is the local momentum in atomic units given by

KLocal = sqrt(2*ELocal)

We assume that beyond the last nucleus that ELocal in atomic units is EMax, and inside the last nucleus ELocal = EMax+1.