SEMICLASSICAL DYNAMICS AND QUANTUM CONTROL IN CONDENSED PHASES - APPLICATION TO I-2 IN A SOLID ARGON MATRIX

A novel scheme is developed which allows for the combination of classi cal sampling techniques and quantum wave packet dynamics to study both the inhomogeneous structural effects and the homogeneous dynamical ef fects in condensed phases. We utilize this methodology to theoreticall y investigate quantum control of the vibrational dynamics of a chromop hore embedded in a condensed-phase environment. We consider control of the vibrational dynamics on an excited electronic state of I-2 that h as been embedded in a low-temperature argon matrix, to compare with th e work of Apkarian, Zadoyan, Martens, and co-workers. The high dimensi onality of such systems precludes the possibility of an exact quantum treatment. To overcome this difficulty we take a semiclassical approac h using Gaussian wave packet dynamics in the weak response regime. We compare the numerical simulation with experimental pump-probe measurem ents of Zadoyan and Apkarian, and we find reasonable agreement over th e short time interval within which we will attempt to control the vibr ational dynamics of the system in this work. Our calculations predict that coherent quantum control is indeed possible in this condensed-pha se system at sufficiently short times and provide a measure of how its effectiveness falls off with time in comparison with the parallel gas -phase case. Finally, we summarize some of the conclusions about quant um control which may be drawn from this work and our other theoretical studies of quantum control in condensed-phase environments.