Adaptive temperature-accelerated dynamics.
Adaptive temperature-accelerated dynamics.
复制标题
自适应温度加速动力学。
作者：
Y. Shim;J. Amar
我们提出了三种自适应的方法来优化高温T（高）在飞行中的温度加速动力学（STIM）模拟。在所有三种方法中，高温定期调整，以最大限度地提高性能。在前两种方法中，调整取决于观察到的事件的数量，而第三种方法取决于迄今为止观察到的最小活化势垒，并且需要作为每个接受的事件的活化势垒E（a）的函数的最佳高温T（high）（opt）（E（a））的先验知识。为了确定T（high）（opt）（E（a））的函数形式，我们对各种金属（Ag、Cu、Ni、Pd和Au）在（100）表面上的亚单层退火进行了广泛的模拟。虽然所有五种金属的结果是不同的，但当它们与熔化温度T（m）成比例时，我们发现它们都位于一条标度曲线上。对于（111）面也得到了类似的结果，尽管在这种情况下标度函数略有不同。为了测试所有三种方法的性能，我们还进行了Ag/Ag（100）退火和生长在T = 80 K的自适应模拟，并与固定的高温模拟的T（高）的不同值进行了比较。我们发现，所有这三种自适应方法的性能通常是一样好或更好的固定的高温度下进行的模拟使用有效的最佳固定的高温度下获得的。此外，我们发现，在我们的自适应模拟中获得的最终高温非常接近我们的结果T（高）（选择）（E（a））。本文还简要讨论了自适应方法对各种非线性仿真的适用性。
We present three adaptive methods for optimizing the high temperature T(high) on-the-fly in temperature-accelerated dynamics (TAD) simulations. In all three methods, the high temperature is adjusted periodically in order to maximize the performance. While in the first two methods the adjustment depends on the number of observed events, the third method depends on the minimum activation barrier observed so far and requires an a priori knowledge of the optimal high temperature T(high)(opt)(E(a)) as a function of the activation barrier E(a) for each accepted event. In order to determine the functional form of T(high)(opt)(E(a)), we have carried out extensive simulations of submonolayer annealing on the (100) surface for a variety of metals (Ag, Cu, Ni, Pd, and Au). While the results for all five metals are different, when they are scaled with the melting temperature T(m), we find that they all lie on a single scaling curve. Similar results have also been obtained for (111) surfaces although in this case the scaling function is slightly different. In order to test the performance of all three methods, we have also carried out adaptive TAD simulations of Ag/Ag(100) annealing and growth at T = 80 K and compared with fixed high-temperature TAD simulations for different values of T(high). We find that the performance of all three adaptive methods is typically as good as or better than that obtained in fixed high-temperature TAD simulations carried out using the effective optimal fixed high temperature. In addition, we find that the final high temperatures obtained in our adaptive TAD simulations are very close to our results for T(high)(opt)(E(a)). The applicability of the adaptive methods to a variety of TAD simulations is also briefly discussed.