Computer simulation of time correlation functions and matter transport coefficients for a model order-disorder alloy
| Autor: | Alan R Allnatt, Z. Qin, E. Loftus Allnatt |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Canadian Journal of Chemistry. 76:1548-1553 |
| ISSN: | 1480-3291 0008-4042 |
| DOI: | 10.1139/cjc-76-11-1548 |
| Popis: | The time correlation functions associated with the Onsager phenomenological coefficients for isothermal matter transport have been calculated by Monte Carlo simulation for a binary system (A,B) at the equiatomic composition according to the Kikuchi-Sato model of an order-disorder alloy with vacancy transport mechanism. The diagonal (AA) time correlation functions are positive, decay monotonically to zero, and exhibit a long time tail where they vary as t-n where t is time; the exponent n varies weakly with temperature at high temperatures and more rapidly as the temperature is lowered through the order-disorder transition temperature. In the region of short-range order the off-diagonal (AB) time correlation function is negative but otherwise shows similar behaviour to the diagonal one, although as the transition temperature is approached n varies more rapidly. At the transition temperature and below, the off-diagonal time correlation function increases from an initial negative value to a maximum where it is positive and then, at later times, decreases to zero. The implications of these observations for approximate theoretical calculations of the phenomenological coefficients are briefly indicated.Key words: diffusion, non-equilibrium phenomena, statistical mechanics, transport properties. |
| Databáze: | OpenAIRE |
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