Bruce R. Johnson

Executive Director, Rice Quantum Institute

Distinguished Faculty Fellow, Department of Chemistry

Research Activities

Wavelet Technology in Quantum Mechanics

The specific aims of interest here are centered on the solution of the molecular Schrödinger equation, motivated by the need for large-amplitude descriptions of the vibrational motion characteristically probed in Dissociative Resonance Raman Spectroscopy (DRRS). While a number of algorithms exist for solving the needed stationary and time-dependent Schrödinger equations, many either waste effort in spatial regions where not much is happening or else require considerable human coaxing. Compact support wavelets can be used to approach a wide variety of Cartesian and curvilinear coordinate problems with systematic accuracy, as has been shown in recent work from this group, and also provide a rational platform for the development of automated methods. As computational resources continually become more powerful, there will be an increasing need for software that minimizes the amount of user intervention. An object-oriented program MultiWavePack is being developed as a platform for these investigations.

Surface-Enhanced Raman Scattering from Metal Nanoparticles

This work aims at calculating molecular near-field response for molecules such as p-mercaptoaniline on silver nanoshells, including vibrational dynamics of multiple Raman-active modes, directionality, field polarization, and polarizability tensors derived from small molecule-metal cluster ab initio calculations. A density matrix formalism is used to include both radiative and non-radiative relaxation processes in spectral simulations of Surface-Enhanced Raman Scattering (SERS), and special attention is paid to the effects of near-resonance in the Raman processes.