GENETIC ALGORITHMS FOR STRUCTURAL CLUSTER OPTIMIZATION

Certain aspects of the methodology of genetic algorithms for global st ructural optimization of clusters were studied. Through systematic inv estigations of Lennard-Jones clusters with up to 100 atoms, several mo difications were made to the genetic algorithm introduced by Deaven an d Ho [Phys. Rev. Lett. 1995, 75, 288]. These modifications result in i mproved efficiency of the search procedure and in certain cases lead t o determination of globally optimal structures that previous genetic a lgorithm studies have not found. The modifications include the followi ng: twinning mutations, add-and-etch processes where a cluster of a gi ven number of atoms is grown beyond that size and subsequently etched, and seeding of the initial parental population with selected structur al motifs, in conjunction with randomly chosen configurations.