CONTROL OF THE ADIABATIC ELECTRONIC STATE IN ABINITIO MOLECULAR-DYNAMICS

Abstract: The problem of keeping the electronic state at its adiabatic value in the course of ab initio molecular dynamics runs with the Car-Parrinello method is discussed. Attention is focused on the difficulties which arise when chemical bonds are broken and formed in the course of the atomic motion. A solution to the problems is the coupling of independent Nose-Hoover thermostats to the up and down spin orbitals. The choice of suitable parameters to control the thermostats is discussed. The success of the method is illustrated in studies of the dissociation/recombination of Na2 and the isomerization of the Na3 molecule by a process of pseudorotation.