ausblenden:
Schlagwörter:
MNDO;
Configuration interaction;
Analytical derivatives;
Z-vector
Zusammenfassung:
Using the Z-vector formalism the analytical gradient of the energy in small CI expansions is derived and implemented for semiempirical MNDO-type methods. The computation time is shown to scale as O(N3) with the size of the system, with the memory requirements growing as O(N2). The evaluation of the analytical gradient is significantly faster than the underlying SCF and CI calculations, so that routine full geometry optimizations at the semiempirical CI level become possible for large systems.
