MOLPRO is able to carry out standard Kohn-Sham DFT calculations
using either the spin-restricted (`ks` or `rks`) or
spin-unrestricted (`uks`) formalisms. Here is a simple example,
which does a local-density approximation (LDA) calculation for
formaldehyde.

***,formaldehyde geometry={ C O , C , rco H1 , C , rch , O , hco H2 , C , rch , O , hco , H1 , 180 } rco=1.182 Ang rch=1.102 Ang hco=122.1789 Degree rks

The exchange-correlation functional, and associated potential, are integrated numerically, and in principle it is necessary to supply parameters to allow the construction of an appropriate grid. However, the grid is built using a model adaptive scheme, and it is normally necessary to specify only the required energy accuracy. This threshold is in turn taken by default from the overall energy convergence threshold, so in most calculations it is not normally necessary to specify anything at all.

Many different exchange and correlation functionals
are contained in the program. They are implemented in a modular
fashion, with both computer code and documentation being built
directly from their mathematical definition. This means that you can
always find the precise definition of a functional in the user manual.
Each functional has a keyword which is used to identify it in the
input file.
The functionals to be used are given one after each other as options
to the `ks` command; for example, the following does a
Kohn-Sham calculation using Becke's exchange functional, and the
Lee-Yang-Parr correlation functional.

`ks,b,lyp`

Another commonly used combination (in fact, the default) is
`ks,s,vwn` which gives LDA (Slater-Dirac exchange,
Vosko-Wilk-Nusair correlation). Finally, the program is aware of
some combinations of functionals, for example `ks,b3lyp` which
is the hybrid B3LYP functional consisting of weighted combinations of
various density functionals together with a fraction of exact
(Hartree-Fock) exchange.

Other options, such as the closed- and open-shell orbitals and the wavefunction symmetry can be defined as explained in section 4.3.

molpro@molpro.net 2018-09-25