Statistical mechanics of monatomic liquids
Statistical mechanics of monatomic liquids
复制标题
单原子液体的统计力学
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
D. Wallace
中科院分区：
文献类型：
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作者：
D. Wallace
元素液体的两个关键实验性质，以及对凝聚系统势能面的分析，从逻辑上将我们引向了单原子液体的动力学理论。在实验上，N离子的离子运动比热约为3Nk，这意味着正常的运动模式约为3N个独立谐振子。这意味着势面包含近乎调和的山谷。每个谷底的平衡构型为{OPEN_QUOTES}结构，{CLOSE_QUOTES}结构为晶态或非晶态，非晶态结构可以具有局部晶体的残余对称性，也可以是无规的。到目前为止，随机结构是最多的，因此主宰了液态的统计力学，对于大N系统，它们的宏观性质在结构类上是一致的。任何结构谷的哈密顿量是静态结构势、简谐简正波和非简谐校正。同样来自实验，熔化的恒密度熵包含了Nk{Delta}的普适无序贡献，这表明随机结构谷具有普适数w{sup N}，其中lnw={Delta}。我们对{Delta}的实验估计为0.80。在准谐近似下，对于目前所有可分析的高温实验数据，液体熵理论与实验一致，在总熵的1{endash}2{%}范围内。文中还提到了该理论的进一步的可检验预测。{版权所有}{ital1997}{italthe American Physitive Society}
Two key experimental properties of elemental liquids, together with an analysis of the condensed-system potential-energy surface, lead us logically to the dynamical theory of monatomic liquids. Experimentally, the ion motional specific heat is approximately 3Nk for N ions, implying the normal modes of motion are approximately 3N independent harmonic oscillators. This implies the potential surface contains nearly harmonic valleys. The equilibrium configuration at the bottom of each valley is a {open_quotes}structure.{close_quotes} Structures are crystalline or amorphous, and amorphous structures can have a remnant of local crystal symmetry, or can be random. The random structures are by far the most numerous, and hence dominate the statistical mechanics of the liquid state, and their macroscopic properties are uniform over the structure class, for large-N systems. The Hamiltonian for any structural valley is the static structure potential, a sum of harmonic normal modes, and an anharmonic correction. Again from experiment, the constant-density entropy of melting contains a universal disordering contribution of Nk{Delta}, suggesting the random structural valleys are of universal number w{sup N}, where lnw={Delta}. Our experimental estimate for {Delta} is 0.80. In quasiharmonic approximation, the liquid theory for entropy agrees with experiment, for all currently analyzable experimental data at elevated temperatures, tomore » within 1{endash}2{percent} of the total entropy. Further testable predictions of the theory are mentioned. {copyright} {ital 1997} {ital The American Physical Society}« less