DFTGRID

Purpose

An object for making integration grids used for DFT calculations.

Synopsis

This routine makes a 3-D atomic integration grid which is a tensor product of a radial grid and a spherical grid.

An integration grid for a molecule can also be made, using a weighted sum of these atomic grids.

In getting a complete molecular grid, an atomic grid at the origin is made using the make_atom_grid routine. For each atom in the molecule, this grid at the origin is copied, re-scaled depending on the Bragg-Slater radii, and then displaced so that its origin is now centred on the atom.

Each re-scaled, displaced grid is then "partitioned". The partitioning modifies the weights of the displaced grid so that effectively it doesn't overlap with the displaced grids on all the other atoms.

The displace and partition of the original "atom" grid is done by the routine rescale_displace_partition.

References

A. D. Becke, J. Chem. Phys., 88, 1988, 2547.

O. Treutler and R. Ahlrichs, J. Chem. Phys., 102, 1995, 346.

Default input data order

There is no associated DFTGRIDVEC type; an input data order has not been defined.

Listing of keywords

becke_m_partition_power= REAL

Read an integer used in smoothing the partition between atomic grids.

  • Must be greater than zero

  • Default value is 2

euler_maclaurin_alpha= REAL

Read the the α parameter used to define the Euler-Maclaurin radial grid.

  • Must be greater than zero

  • Default value is 2

euler-maclaurin_alpha= REAL

Equivalent to euler_maclaurin_alpha=.

euler_maclaurin_m= REAL

Read the the α parameter used to define the Euler-Maclaurin radial grid.

  • Must be greater than zero

  • Default value is 2

euler-maclaurin_m= REAL

Equivalent to euler_maclaurin_m=.

gauss_chebyshev_alpha= REAL

Read the the α parameter used to define the Gauss-Chebyshev radial grid.

  • Must be greater than zero

  • Default value is 3

gauss-chebyshev_alpha= REAL

Equivalent to gauss_chebyshev_alpha=.

gauss_chebyshev_m= REAL

Read the the m parameter used to define the Gauss-Chebyshev radial grid.

  • Must be greater than zero

  • Default value is 1

gauss-chebyshev_m= REAL

Equivalent to gauss_chebyshev_m=.

radial_grid_kind= STR

Read the kind of radial grid to be used for the radial part of the numerical quadrature grid.

  • Allowed options are gauss-chebyshev or euler_maclaurin

  • Default is gauss-chebyshev

radial_grid_order= INT

Read a the number of radial quadrature points to be used.

  • Must be greater than zero

  • Default value is 60

spherical_grid_kind= STR

Read the kind of spherical grid to be used for the angular part of the numerical quadrature grid.

  • Allowed optins: only lebedev so far

  • Not surprisingly, the default value is lebedev

  • To input the kind of radial integration grid see radial_grid_kind=

spherical_grid_order= INT

Read an integer which determines the "order" or accuracy of the angular quandrature grid..

  • Allowed lebedev values are 23, 25, 27, 29, 35, 41, 47, 53, 59

  • Default lebedev value is 35

put

Print out information about the DFT integration grid to stdout in human readable form.