CamCASP/Programming/4
CamCASP => Programming => Rotations
The theory of integral and MO rotations has been described in The DF INTEGRAL module . This is a collection of odds and ends related to rotations.
DALTON
MOs from DALTON don't seem to be rotationally invariant. Consider the following example:
water dimer. Sadlej/PBE0/AC MC basis type. Aux basis: JK-tzvpp. Geom: R=2.4 Ang in min-orientation.
I noticed a discrepancy in the e-e and e-n energies (parts of <math>E^{(1)}_{\rm elst}</math>) when calculated in the following ways:
- MOs calculated in reference geometry and rotated with molecule.
- Molecules rotated and MOs calculated in already rotated geometry.
These should be equivalent. And the MOs should be equivalent and related by a Wigner rotation matrix. This was not the case and I found small, but noticable differences that led to small differences in the e-n energies (there should also be differences in the e-e energies, but I still have to trace other errors here, so cannot be sure).