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Center for Nonlinear Studies |
Optical Spectroscopy of Polyatomic Materials: First Principles Calculations of Anharmonic Potential Energy Surfaces
An ability to model anharmonic couplings between vibrational modes in condensed phase polyatomic molecular systems is crucial for understanding and controlling a variety of photo-chemical and photo-physical processes including the vibrational energy transports. To address this issues, we have developed a first principles (DFT) based approach to the anharmonic potential energy surfaces reconstruction in materials possessing translational symmetries. This should allow us to simulate spectroscopic signatures of the energy transport in the frequency resolved temperature-dependent infrared and Raman spectra, and in the time-resolved nonlinear, e.g., photon-echo, responses of anharmonically coupled vibrational modes. To validate the methodology, we have performed the simulations on pentaerythritol tetranitrate (PETN) molecular crystalline material.