Related papers: Structural stability and lattice dynamics of SiO2 …

By performing constant-pressure variable-cell ab initio molecular dynamics simulations we find a quadrupolar orthorhombic structure, of $Pca2_1$ symmetry, for the broken symmetry phase (phase II) of solid H2 at T=0 and P =110 - 150 GPa. We…

Titanium dioxide, TiO$_2$, has multiple applications in catalysis, energy conversion and memristive devices because of its electronic structure. Most of these applications utilize the naturally existing phases: rutile, anatase and brookite.…

We recently proposed a high-pressure and high-temperature P-62m-symmetry polymorph for CaF2 on the basis of ab-initio random structure searching and density-functional theory calculations [Phys. Rev. B 95, 054118 (2017)]. We revisit this…

Recently, Pei et al. (arXiv2105.13250) reported that ambient pressure ${\beta}$-MoB$_2$ exhibits a phase transition to ${\alpha}$-MoB$_2$ (space group: $P6/mmm$) at pressure P~70 GPa and this high-pressure phase is a high-temperature…

Properties of the $\omega$ structure are investigated for 27 transition elements from the viewpoints of thermodynamical and mechanical stability based on first-principles calculations. The thermodynamical stability of the $\omega$ structure…

First-principles modeling of a GeO2/Ge(001) interface reveals that sixfold GeO2, which is derived from cristobalite and is different from rutile, dramatically reduces the lattice mismatch at the interface and is much more stable than the…

The crystal structure of CO2 filled pure SiO2 LTA zeolite has been studied at high pressures and temperatures using synchrotron based x ray powder diffraction. Its structure consists of 13 CO2 guest molecules, 12 of them accommodated in the…

The simple alkali metal Na, that crystallizes in a body-centred cubic structure at ambient pressure, exhibits a wealth of complex phases at extreme conditions as found by experimental studies. The analysis of the mechanism of stabilization…

Lithium transition metal phospho-olivines are useful electrode materials, owing to their stability, high safety, low cost and cyclability. We report phonon studies using neutron inelastic scattering experiments, ab-initio density functional…

The alpha cluster states of 16C are investigated by using the antisymmetrized molecular dynamics. It is shown that two different types of alpha cluster states exist: triangular and linear-chain states. The former has an approximate…

Hexagonal BaTiO_3 undergoes a structural phase transition to an orthorhombic C222_1 phase at T_0 = 222 K. The transition is driven by a soft optical mode with E_2u symmetry whose couplings force the appearance of a spontaneous E_2g strain…

Metastable nanostructures are kinetically trapped in local energy minima featuring intriguing surface and material properties. To unleash their potential, there is a need for non-equilibrium processes capable of stabilizing a large range of…

We study the low-temperature behavior of a simple cluster-crystal forming system through simulation. The phase behavior is found to be hybrid between the Gaussian core and penetrable sphere models. The system additionally exhibits a series…

We have used an effective model of ferroelectric PbTiO$_{3}$, which displays a representative soft mode-driven phase transition, to investigate how different features of the potential-energy surface affect the transition temperature $T_{\rm…

The theoretical formalism of the local density approximation (LDA) to density functional theory (DFT) has been used to study the electronic and geometric structures of SimCn (1<=m, n<=4;n<=m) clusters. An all electron 6-311++G** basis set…

A cascade of phase transitions from square to hexagonal lattice is studied in 2D system of particles interacting via core-softened potential. Due to the presence of two length-scales of repulsion, different local configurations with four,…

We present a study of the spectral properties like the energy spectrum, the eigenmodes and density of states of a classical finite system of two-dimensional (2D) charged particles which are confined by a quadratic potential. Using the…

Raman spectroscopy experiments on single crystals of CuSb2O6 and CoSb2O6 quasi-one-dimensional antiferromagnets with trirutile crystal structure were performed, with a focus on the first material. The observed Raman-active phonon modes and…

The nature of the lattice instability connected to the structural transition and superconductivity of (Sr,Ca)$_3$Ir$_4$Sn$_{13}$ is not yet fully understood. In this work density functional theory (DFT) calculations of the phonon…

Silver-based chalcohalide anti-perovskites (CAP), Ag$_{3}$BC (B = S, Se; C = Cl, Br, I), represent an emerging family of energy materials with intriguing optoelectronic, vibrational and ionic transport properties. However, the structural…