General order imaginary time correlation functions and imaginary frequency susceptibilities |
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Authors: | S Baer |
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Institution: | Department of Physical Chemistry , The Hebrew University , Jerusalem, Israel |
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Abstract: | Certain periodicity properties of general order imaginary time (‘temperature’) correlation functions can be used to represent the n + 1th order van der Waals pair interactions as a multiple Fourier series whose coefficients are nth-order imaginary frequency susceptibilities of the two molecules. This representation is a generalization to higher orders of the standard expression for the second-order van der Waals pair interaction in terms of imaginary frequency polarizabilities. The fourth-order dispersion energy for spherical molecules in their ground state is obtained as a sum of multiple integrals over imaginary frequencies of certain products of dynamic linear and cubic polarizabilities of the two molecules. |
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