Regular Article - Solid State and Materials
Efficiency of extremal optimization to find the ground state of Coulomb glass system at small disorder
Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology, 201307, Noida, Uttar Pradesh, India
Accepted: 17 February 2023
Published online: 11 March 2023
In this paper, we have used extremal optimization to find the ground state of the two-dimensional lattice Coulomb glass model. The system is modeled as a spin system interacting via long range Coulomb interactions. This system for disorders less than the critical disorder has antiferromagnetic ordering at zero temperature. The number of electrons in the system is conserved, and hence the total magnetization of the system is conserved. The optimization procedure assigns cost to only the nearest neighbor pair of opposite spins instead all pairs of opposite spins leading to decrease in time and space complexity of the algorithm. This novel approach takes electron conservation and the mechanism of formation of domains into account. The selection of pair of sites for spin flip is done similarly to the extremal optimization defined for Glauber spin glass system. The new algorithm has very good efficiency in achieving the ground state. In cases where the ground state is not achieved, the system gets stuck in a metastable state consisting of mainly two large domains. Using activity graphs, we show that the domains are pinned at certain locations.
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