Application of the mixed time-averaging semiclassical initial value representation method to complex molecular spectra

Abstract

The recently introduced mixed time-averaging semiclassical initial value representation molecular dynamics method for spectroscopic calculations [M. Buchholz, F.Grossmann, and M. Ceotto, J. Chem. Phys. 144, 094102 (2016)] is applied to systems with up to 61 dimensions, ruled by a condensed phase Caldeira-Leggett model potential. By calculating the ground state as well as the first few excited states of the system Morse oscillator, changes of both the harmonic frequency and the anharmonicity are determined. The method faithfully reproduces blueshift and redshift effects and the importance of the counter term, as previously suggested by other methods. Differently from previous methods, the present semiclassical method does not take advantage of the specific form of the potential and it can represent a practical tool that opens the route to direct ab initio semiclassical simulation of condensed phase systems. 1 arXiv:1708.03454v1 [quant-ph]

Qual È La Più Piccola Goccia D’acqua?

“…Nel mio gruppo di ricerca (https://sites.unimi.it/ceotto/) abbiamo recentemente sviluppato dei metodi basati sulla meccanica semiclassica [5][6][7][8][9][10][11][12][13], grazie ad un finanziamento dell'European Research Council. In particolare, abbiamo esteso le teorie semiclassiche al calcolo degli spettri vibrazionali di sistemi molecolari complessi e supramolecolari [14][15][16][17][18][19][20][21]. La meccanica semiclassica, come si può comprendere dalla Fig.…”

Machine Learning for Vibrational Spectroscopy via Divide-and-Conquer Semiclassical Initial Value Representation Molecular Dynamics with Application to N-Methylacetamide

“…For example, a collection of +1 values allows one to enhance the ZPE signal (together with the even transitions), while a selected j = −1 and the remaining i =j = +1 enhances the odd transition of the j − th mode. 43 MC SCIVR has been successfully applied to the study of several systems, [44][45][46][47][48][49][50][51][52][53][54][55] including the different conformers of the glycine amino acid. 44 To improve with respect to the harmonic initial conditions of Eq.s (7), a preliminary adiabatic switching warm up can be implemented with the result that frequency estimates are generally more accurate and complications due to deterministic chaos are largely avoided.…”

Machine learning for vibrational spectroscopy via divide-and-conquer semiclassical initial value representation molecular dynamics with application to N-methylacetamide

“…For example, a collection of +1 values allows one to enhance the zero-point energy (ZPE) signal (together with the even transitions), while a selected ϵj = −1 and the remaining ϵi≠j = +1 enhance the odd transition of the jth mode. 43 The MC SCIVR has been successfully applied to the study of several systems, [44][45][46][47][48][49][50][51][52][53][54][55] including the different conformers of the glycine amino acid. 44 To improve with respect to the harmonic initial conditions of Eq.…”