43.3 Using the SLAPAF program for geometry optimization

It is optionally possible to use the SLAPAF program written by Roland Lindh for geometry optimizations. This is done by prepending the optimization method with 'SL'. The following methods are supported:

SLRF

Use the rational function approximation;

SLNR

Use the Newton-Raphson method;

SLC1

Use the C1-DIIS method;

SLC2

Use the C2-DIIS method.

When using DIIS methods (SLC1 or SLC2), the DIIS parameters are specified in the same way as in standard molpro optimizer.

There are some differences when using the SLAPAF program:

1)

It is not possible to use Z-matrix coordinates in the optimization.

2)

Instead, one can explicitly define internal coordinates to be varied or fixed.

3)

Additional constraints can be imposed on the converged geometry in a flexible way.