Anharmonic Vibrational Eigenfunctions and Infrared Spectra from Semiclassical Molecular Dynamics

Abstract

We describe a new approach based on semiclassical molecular dynamics that allows to simulate infrared absorption or emission spectra of molecular systems with inclusion of anharmonic intensities. This is achieved from semiclassical power spectra by computing first the vibrational eigenfunctions as a linear combination of harmonic states, and then the oscillator strengths associated to the vibrational transitions. We test the approach against a 1D Morse potential and apply it to the water molecule with results in excellent agreement with discrete variable representation quantum benchmarks. The method does not require any grid calculations and it is directly extendable to high dimensional systems. The usual exponential scaling of the basis set size with the dimensionality of the system can be avoided by means of an appropriate truncation scheme. Furthermore, the approach has the advantage to provide IR spectra beyond the harmonic approximation without losing the possibility of an intuitive assignment of absorption peaks in terms of normal modes of vibration.

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Cited by in corpus (9)

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• Improved semiclassical dynamics through adiabatic switching trajectory sampling
• Reduced Rovibrational Coupling Cartesian Dynamics for Semiclassical Calculations: Application to the Spectrum of the Zundel Cation
• Vibrational Investigation of Nucleobases by Means of Divide and Conquer Semiclassical Dynamics
• Semiclassical vibrational spectroscopy with Hessian databases
• Representing Molecular Ground and Excited Vibrational Eigenstates with Nuclear Densities obtained from Semiclassical Initial Value Representation Molecular Dynamics
• The quantum nature of ubiquitous vibrational features revealed for ethylene glycol
• Quantum dissipative systems beyond the standard harmonic model: features of linear absorption and dynamics
• Degeneracy and coherent states of the two-dimensional Morse potential