Molecular Dynamics in Shape Space and Femtosecond Vibrational Spectroscopy of Metal Clusters

We introduce a method of molecular dynamics in shape space aimed at metal clusters. The ionic degrees of freedom are described via a dynamically deformable jellium with inertia parameters derived from an incompressible, irrotational flow. The shell correction method is used to calculate the electronic potential energy surface underlying the dynamics. Our finite-temperature simulations of Ag14 and its ions, following the negative-to-neutral-to-positive scheme, demonstrate the potential of pump-and-probe ultrashort laser pulses as a spectroscopy of cluster shape vibrations. The study of the motion of an incompressible and irrotational fluid mass with an ellipsoidal surface has its origins in investigations on the theory of the shape of the Earth. Such studies started with Newton and Maclaurin and were continued by others, in particular for the case of a Varying surface by Dirichlet, Dedekind, and Riemann (see ref 1). In these early studies in the realm of astronomy and astrophysics, the forces were due to the gravitational field. More recently, similar ideas were used in nuclear physics in investigations of low-energ