[CPMD-list] BFGS update

[Salomon Billeter]

Hi,

for the nuclear Hessian, both BFGS and Powell updates are implemented.
However, Powell is only called if RFO (not P-RFO which uses its own Hessian
and its own implementation of the Powell formula) is used and a saddle
point is searched for. In all other cases, the BFGS update is used because
it preserves the positive definiteness of the Hessian which is a
prerequisite of a energy minimum. Why do you want to use Powell with GDIIS?

Best regards,
Salomon