Naskar Pulak, Talukder Srijeeta, Chaudhury Pinaki
Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata - 700 009, India.
Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata - 700 032, India.
Phys Chem Chem Phys. 2017 Apr 5;19(14):9654-9668. doi: 10.1039/c7cp00655a.
In this communication, we would like to discuss the advantages of adaptive mutation simulated annealing (AMSA) over standard simulated annealing (SA) in studying the Coulombic explosion of (CO) clusters for n = 20-68, where 'n' is the size of the cluster. We have demonstrated how AMSA itself can overcome the predicaments which can arise in conventional SA and carry out the search for better results by adapting the parameters (only when needed) dynamically during the simulations so that the search process can come out of high energy basins and not go astray for better exploration and convergence, respectively. This technique also has in-built properties for getting more than one minimum in a single run. For a (CO) cluster system we have found the critical limit to be n = 43, above which the attractive forces between individual units become greater in value than that of the large repulsive forces and the clusters stay intact as the energetically favoured isomers. This result is in good concurrence with earlier studies. Moreover, we have studied the fragmentation patterns for the entire size range and we have found fission type fragmentation as the favoured mechanism nearly for all sizes.
在本通讯中，我们想讨论自适应变异模拟退火算法（AMSA）相较于标准模拟退火算法（SA）在研究n = 20 - 68的（CO）团簇库仑爆炸时的优势，其中“n”是团簇的大小。我们已经证明了AMSA自身如何能够克服传统SA中可能出现的困境，并通过在模拟过程中动态地（仅在需要时）调整参数来进行更好结果的搜索，以便搜索过程能够分别从高能盆地中跳出且不会误入歧途，从而实现更好的探索和收敛。该技术还具有在单次运行中获得多个最小值的内在特性。对于（CO）团簇系统，我们发现临界极限为n = 43，在此之上，单个单元之间的吸引力在数值上大于大的排斥力，并且团簇作为能量上有利的异构体保持完整。这一结果与早期研究高度一致。此外，我们研究了整个尺寸范围内的碎片化模式，并且发现几乎对于所有尺寸，裂变型碎片化都是首选机制。
