14 INTEGRATION

Before starting any energy calculations,
the geometry and basis set must be defined
in `GEOMETRY` and `BASIS` blocks, respectively.
By default, two electron integrals are evaluated once and stored on
disk. This behaviour may be overridden by using the input command
`gdirect` to force evaluation of integrals on the fly.
MOLPRO checks if the one-and two-electron integrals are available for
the current basis set and geometry, automatically computing them if necessary.
The program also recognizes automatically
if only the nuclear charges have been changed, as is the case in counterpoise
calculations. In this case, the two-electron integrals are
not recomputed.

molpro@molpro.net 2019-01-15