The electronic adiabatic-to-diabatic transformation matrix and the Wigner rotation matrix

In this publication we consider electronically multi-fold degeneracy with t he aim of revealing the connection between the adiabatic-to-diabatic transf ormation (ADT) matrices and Wigner's irreducible representation of the rota tion group. To form the connection we constructed simplified models of two- , three- and four-states all (electronically) degenerate at a single point and employed the relevant non-adiabatic coupling matrices (NACMs). We found that once these matrices were properly quantized [Chem. Phys. 259, (2000) 123] the ADT matrices and Wigner's d(i)-rotation matrices are related via a similarity transformation. (C) 2001 Elsevier Science B.V. All rights reser ved.