Inverse simulated annealing: Improvements and application to amorphous InSb

Abstract

An improved inverse simulated annealing method is presented to determine the structure of complex disordered systems from first principles in agreement with available experimental data or desired predetermined target properties. The effectiveness of this method is demonstrated by revisiting the structure of amorphous InSb. The resulting network is mostly tetrahedral and in excellent agreement with available experimental data.

Influence of the exchange and correlation functional on the structure of amorphous InSb and In3SbTe2 compounds

“…32,43 The ISA method is a Monte Carlo (MC) annealing scheme, designed to combine the accuracy of ab initio calculations with the reverse MC technique 44,45 in order to efficiently generate low energy structures in best agreement with available experimental data. Here we will use ISA merely as a minimization tool, i.e., without any experimental constraints.…”

“…As such, ISA has been shown to be quite competitive in the application to amorphous phases with respect the more standard annealing procedure using molecular dynamics in the sense that it yields very similar structures but in significantly less computation time. 43 The hybrid MC-based ISA method introduced in our previous works 32,43 is a "fuzzy" hybrid MC method with all atom trial moves generated by a single, energy conserving, velocity-Verlet MD step but with a randomly chosen time step dt ∈ (0, dt max ), where dt max is adjusted on-the-fly to achieve an acceptance of 50%. To perform isobaric simulations, also volume moves are allowed with an acceptance probability equal to that in standard MC simulation within the NPT ensemble.…”

“…46 However, it later turned out that the mostly tetrahedral model of Ref. 32 was actually resulting from the use of the too contracted basis set rather than from the long quenching time of 350 ps. 32 In fact, simulations with similarly long quenches and the accurate DZVP basis set invariably lead to models with a large fraction of octahedrallike local geometries, in one case also lower in energy than the mostly tetrahedral-like model.…”

“…32 was actually resulting from the use of the too contracted basis set rather than from the long quenching time of 350 ps. 32 In fact, simulations with similarly long quenches and the accurate DZVP basis set invariably lead to models with a large fraction of octahedrallike local geometries, in one case also lower in energy than the mostly tetrahedral-like model. We remark that the accurate DVZP and the TZVP basis sets used here have been extensively validated against calculations with a plane wave basis sets and the same pseudopotentials which actually revealed that the more contracted basis set used only in the quenching protocol employed in Ref.…”

“…15 For the sake of completeness we have also revisited with the use of the BLYP functional the structural properties of the amorphous phase of the binary InSb compound that we have simulated with the PBE functional in our previous works. 31,32 As opposed to what occurs in GeSbTe alloys, it turns out that in the case of InSb the use of the BLYP functional brings the theoretical results in better agreement with experiment by favoring the tetrahedral-like environment with respect to the octahedral-like ones. A similarly larger fraction of tetrahedral configurations is also found in the BLYP models of the ternary InSbTe alloys with respect to those generated with the PBE functional.…”