SPIN DYNAMICS UNDER THE HAMILTONIAN VARYING WITH TIME IN DISCRETE STEPS - MOLECULAR DYNAMICS-BASED SIMULATION OF ELECTRON AND NUCLEAR-SPIN RELAXATION IN AQUEOUS NICKEL(II)

A method of calculating the time correlation functions for electron sp in is proposed, based on solving the time-dependent Schrodinger equati on for a spin Hamiltonian that contains a term varying randomly in dis crete time steps. It is applied to the study of electron spin relaxati on in aqueous solution of nickel(II) ions with S=1. The random term in the spin Hamiltonian in this case is the zero-field splining (ZFS) in teraction. The method is evaluated by an application to a model system (the pseudorotation model) for which an analytical solution to the el ectron spin relaxation problem is known. The same method is then emplo yed to study the electron and nuclear spin dynamics in a system where the time variation of the zero-field splitting is obtained by a combin ation of ab initio quantum chemistry and molecular dynamics simulation s. (C) 1996 American Institute of Physics.