- Always start from neighbouring geometry orbitals when available (this is the default).
- The convergence algorithm is more stable when there are no
`CLOSED`orbitals, i.e., orbitals doubly occupied in all configurations, but fully optimized. Thus a reasonable approach is to make an initial calculation with`CLOSED`replaced by`FROZEN`(all doubly occ. frozen). - If still no success, you can switch off the coupling between CI
coefficients and orbital rotations for a few iterations, e.g.:
{

`ITERATIONS;DO,UNCOUPLE,1,TO,2;`}and/or disable the simultaneous optimization of internal orbitals & CI, e.g.:

{

`ITERATIONS;DONT,INTERNAL,1,TO,2;`}

`IPRINT,MICRO;`

in the data. Also consider the general remarks at the beginning of this chapter. For the
details of the algorithms used, see J. Chem. Phys 82, 5053 (1985); Chem. Phys. Letters 115,
259 (1985); Advan. Chem. Phys. 59, 1 (1987);

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molpro@molpro.net 2015-10-01