First-principles calculation of nuclear resonance vibrational spectra
We present a ‘first-principles’ methodology for the calculation of the parameters that are required for the simulation of nuclear resonance vibrational spectra (NRVS) of molecular systems. Formulae are given for the intensities of vibrational transitions corresponding to the so-called single- and double-phonon contributions to the NRVS signal. The method is also valid for those vibrations that are not in the high-frequency/low-temperature limit. We have rigorously treated the issue of orientational averaging of the Lamb–Mössbauer factor and the effect of the neglect of its anisotropy on the calculated NRVS pattern. Normal mode composition factors are determined in a compact form as appropriate components of an orthogonal matrix that diagonalizes the Hessian matrix. The method is illustrated by simulating the NRVS spectra and the partial vibrational density of states of [FeO(H2O)5]2+ on the basis of vibrational frequencies and normal mode composition factors obtained from density functional theory (DFT) calculations.
PACS numbers3115Ar 3320Tp 2930Kv 8280Ej
KeywordsFirst-principles calculation Nuclear resonance vibrational spectra Partial vibrational density of states
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