D R Reichman | PubMed Health

PubMed2001

Self-consistent mode-coupling theory for self-diffusion in quantum liquids.

A closed, self-consistent equation for the velocity autocorrelation function of a quantum liquid within the framework of a quantum mode-coupling theory is derived. The solution of the quantum generalized Langevin equation requires static input which is generated by an appropriate path-integral Monte Carlo scheme. In order to assess the accuracy of our approach we have studied the self-diffusion process of liquid para-hydrogen at two thermodynamic state points. Quantitative agreement for the self-diffusion constant is obtained in comparison to experimental measurements and other theoretical predictions.

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PubMed2001

Mode-coupling theory of the fifth-order Raman spectrum of an atomic liquid.

A fully microscopic molecular hydrodynamic theory for the two-dimensional (fifth-order) Raman spectrum of an atomic liquid (Xe) is presented. The spectrum is obtained from a simple mode-coupling theory by projecting the dynamics onto bilinear pairs of fluctuating density variables. Good agreement is obtained in comparison with recently reported molecular dynamics simulation results. The microscopic theory provides an understanding of the timescales and molecular motions that govern the two-dimensional signal. Predictions are made for the behavior of the spectrum as a function of temperature and density. The theory shows that novel signatures in the two-dimensional Raman spectrum of supercritical and supercooled liquids are expected.

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