Keyes T, Chowdhary J
Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Sep;64(3 Pt 1):032201. doi: 10.1103/PhysRevE.64.032201. Epub 2001 Aug 21.
The self-diffusion constant D is expressed in terms of transitions among the local minima (inherent structures, IS) of the N-body potential-energy surface or landscape, and their correlations. The formulas are evaluated and tested against simulation in the supercooled, unit-density Lennard-Jones liquid. The approximation of uncorrelated IS-transition (IST) vectors D0, greatly exceeds D for the highest T, but merges with simulation at reduced T approximately 0.50, close to the estimated mode-coupling temperature T(c). Since uncorrelated IST's are associated with a hopping mechanism, the condition D approximately D0 provides a new way to identify the crossover to hopping. The results suggest that theories of diffusion in deeply supercooled liquids may be based on weakly correlated IST's.
自扩散常数D是根据N体势能面或态势的局部极小值（固有结构，IS）之间的跃迁及其相关性来表示的。这些公式在过冷的单位密度 Lennard-Jones 液体中进行了评估和模拟测试。不相关的IS跃迁（IST）向量D0的近似值在最高温度时大大超过D，但在约为0.50的约化温度下与模拟结果合并，接近估计的模式耦合温度T(c)。由于不相关的IST与跳跃机制相关联，D约等于D0的条件为识别向跳跃的转变提供了一种新方法。结果表明，深度过冷液体中扩散的理论可能基于弱相关的IST。
