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Spectroscopic fingerprints of toroidal nuclear quantum delocalization via ab initio path integral simulations
Author(s) -
Schütt Ole,
Sebastiani Daniel
Publication year - 2012
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23206
Subject(s) - delocalized electron , physics , momentum (technical analysis) , ab initio , position and momentum space , quantum , path integral formulation , distribution function , molecular dynamics , angular momentum , quantum mechanics , atomic physics , finance , economics
We investigate the quantum‐mechanical delocalization of hydrogen in rotational symmetric molecular systems. To this purpose, we perform ab initio path integral molecular dynamics simulations of a methanol molecule to characterize the quantum properties of hydrogen atoms in a representative system by means of their real‐space and momentum‐space densities. In particular, we compute the spherically averaged momentum distribution n ( k ) and the pseudoangular momentum distribution n ( k θ ). We interpret our results by comparing them to path integral samplings of a bare proton in an ideal torus potential. We find that the hydroxyl hydrogen exhibits a toroidal delocalization, which leads to characteristic fingerprints in the line shapes of the momentum distributions. We can describe these specific spectroscopic patterns quantitatively and compute their onset as a function of temperature and potential energy landscape. The delocalization patterns in the projected momentum distribution provide a promising computational tool to address the intriguing phenomenon of quantum delocalization in condensed matter and its spectroscopic characterization. As the momentum distribution n ( k ) is also accessible through Nuclear Compton Scattering experiments, our results will help to interpret and understand future measurements more thoroughly. © 2012 Wiley Periodicals, Inc.