| 研究実績の概要 |
The aim of this project is to generalize Kirkwood-Buff (KB) theory, which is widely used for liquids and solutions, to crystalline solids. In the first year we have achieved the following two major goals.
1) We have used the finite-volume KB formalism to calculate the Madelung energy of ionic crystals. The new method is quite efficient and converges for any structure. We have shown that the leading surface term, which can be interpreted as the orientation averaged surface energy of ionic solids, has a simple, universal (i.e. structure independent) expression. The results of this study have been submitted for publication in Phys. Rev. B [P. Krueger, "Ensemble averaged Madelung energies of finite volumes and surfaces", https://arXiv.org/abs/2003.03721].
2) We have successfully applied, for the first time ever, KB theory to crystals (solid Ar). For the perfect crystal, where the exact result is known, we have shown that the finite volume KB integral converges to the correct result (while the usual, so-called running KB integral, diverges severely). This proves that our new KB theory can indeed be used to study crystalline solids. Second we have studied the temperature dependence of the KB integrals of solid Argon numerically using pair-distribution functions obtained by Monte-Carlo simulations. From this the compressibility of solid Argon has been obtained and the result was found in good agreement with the value obtained by other methods.
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