Global geometry optimization of (Ar)n and B(Ar)n clusters using a modified genetic algorithm

A modified deterministic/stochastic genetic algorithm (DS‐GA) method is proposed for the determination of the global minimum of atomic clusters described by pairwise analytic interaction potentials. Our modification of the standard GA method involves a coarse local minimization of each member of the population at every generation, as well as including the gradient into the fitness function. For Lennard‐Jones (Ar)n clusters with n<30, the DS‐GA converges far more quickly to the global minimum than either conventional GA methods or random search procedures. An application of this DS‐GA is made to heterogeneous clusters of B(2P) with multiple Ar atoms. The interaction potential is given by the lowest state of a 3×3 electronic Hamiltonian. The Ar–Ar potential and the lower energy (Π state) B–Ar potential are very similar. In contrast, the higher energy (Σ state) B–Ar interaction is essentially repulsive. Consequently, the B atom is nearly always found to substitute for one of the atoms in the corresponding (A...