Sampling Polymorphs of Ionic Solids using Random Superlattices

Apparent scarcity of low-density polymorphs of inorganic solids.

For most inorganic solids, very few dense polymorphs and no low-density polymorphs are observed. Taking a wide range of tetrahedrally-coordinated binary solids (e.g., ZnO, GaN) as a prototypical system, we show that the apparent scarcity of low- density polymorphs is not due to significant structural or energetic limitations. Using databases of periodic networks as sources of novel crystal stru...

Pharmaceutical Salts: Solids to Liquids by Using Ionic Liquid Design

Computing equations of state for ionic solids

Two diierent theoretical approaches to the total energy of solids have been applied to describe the equations of state (EOS) of ionic halides and oxides. The rst one is the ab initio Perturbed Ion (aiPI) model, a quantum-mechanical technique that solves the Hartree-Fock equations of a crystal in a localized Fock space. The second one is an interatomic force model implemented in a new computatio...

Symmetry and random sampling of symmetry independent configurations for the simulation of disordered solids.

A symmetry-adapted algorithm producing uniformly at random the set of symmetry independent configurations (SICs) in disordered crystalline systems or solid solutions is presented here. Starting from Pólya's formula, the role of the conjugacy classes of the symmetry group in uniform random sampling is shown. SICs can be obtained for all the possible compositions or for a chosen one, and symmetry...

An Unbiased Estimator of the Variance of Simple Random Sampling Using Mixed Random-Systematic Sampling

Systematic sampling is a commonly used technique due to its simplicity and ease of implementation. The drawback of this simplicity is that it is not possible to estimate the design variance without bias. There are several ways to circumvent this problem. One method is to suppose that the variable of interest has a random order in the population, so the sample variance of simple random sampling ...