Displaced path integral formulation for the momentum distribution of quantum particles

Lin Lin, Joseph A. Morrone, Roberto Car, Michele Parrinello

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

The proton momentum distribution, accessible by deep inelastic neutron scattering, is a very sensitive probe of the potential of mean force experienced by the protons in hydrogen-bonded systems. In this work we introduce a novel estimator for the end-to-end distribution of the Feynman paths, i.e., the Fourier transform of the momentum distribution. In this formulation, free particle and environmental contributions factorize. Moreover, the environmental contribution has a natural analogy to a free energy surface in statistical mechanics, facilitating the interpretation of experiments. The new formulation is not only conceptually but also computationally advantageous. We illustrate the method with applications to an empirical water model, ab initio ice, and one dimensional model systems.

Original languageEnglish (US)
Article number110602
JournalPhysical review letters
Volume105
Issue number11
DOIs
StatePublished - Sep 9 2010

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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