Structure prediction based onab initiosimulated annealing for boron nitride

Abstract

Possible crystalline modifications of chemical compounds at low temperatures correspond to local minima of the energy landscape. Determining these minima via simulated annealing is one method for the prediction of crystal structures, where the number of atoms per unit cell is the only information used. It is demonstrated that this method can be applied to covalent systems, at the example of boron nitride, using ab initio energies in all stages of the optimization, i.e. both during the global search and the subsequent local optimization. Ten low lying structure candidates are presented, including both layered structures and 3d-network structures such as the wurtzite and zincblende types, as well as a structure corresponding to the β-BeO type.

Emergence of a few distinct structures from a single formal structure type during high-throughput screening for stable compounds: The case of RbCuS and RbCuSe

“…Several global optimization methods are currently widely used to search for the lowest energy structure of a solid by exploring in an unbiased fashion the Born-Oppenheimer surface of a solid calculated by DFT. These computational appraoches include evolutionary algorithms [30][31][32][33][34] , particle swarm optimization, 35 methods based on molecular dynamics, such as simulated annealing 36 , minima hopping, 37 and metadynamics 38 . Also a search approach based on the local energy minimization of randomly generated structures 39 has been successfully applied to numerous materials.…”

Structure Prediction for PbS and ZnO at Different Pressures and Visualization of the Energy Landscapes

“…While for many ionic systems, such as TiO 2 [12], MgSiO 3 [13], halides [14], and sulfides of the alkali metals [15], or the earth alkaline halides [16] and oxides [17,18], the most important modifications can be identified using an empirical potential energy landscape, this is no longer true for systems with covalent bonds, complex ions, or nonbonding electron pairs. For such systems, the energy calculation during the global optimization must be performed on the ab initio level [9,[19][20][21][22][23]. As an example, we have studied PbS, where steric electron pairs may play a role.…”

Apparent Scarcity of Low-Density Polymorphs of Inorganic Solids

“…Furthermore, for BN, which is not strictly a TBS as it crystallizes under ambient conditions as the three-connected h-BN polymorph, ABW-BN (again with a 4CN originally found as a silicate) and BCT-BN have been predicted [22]. Such studies have not exploited the huge resource of enumerated 4CNs, but have instead derived TBS polymorphs based on methods inspired by physical processes (e.g., simulated thermal [22] and mechanical annealing [17], cluster assembly [20,21]). Arguably, the most thorough study of the energy landscape of any TBSlike system to date was that recently applied to BN [22] which sampled systems with up to only eight atoms per unit cell finding only two hypothetical TBS polymorphs (see above).…”

“…Such studies have not exploited the huge resource of enumerated 4CNs, but have instead derived TBS polymorphs based on methods inspired by physical processes (e.g., simulated thermal [22] and mechanical annealing [17], cluster assembly [20,21]). Arguably, the most thorough study of the energy landscape of any TBSlike system to date was that recently applied to BN [22] which sampled systems with up to only eight atoms per unit cell finding only two hypothetical TBS polymorphs (see above). Evidently, to date, such studies have yielded only a very small number of hypothetical TBS polymorphs with respect to those derived for silica from the enumeration of 4CNs [3][4][5][6][7].…”