Topology of the phonon dispersion in α-cristobalite

Theory of Nonlinear s-Polarized Phonon-Polaritons in Multilayered Structures

A theory is presented for the dispersion relations of the nonlinear phonon-polaritons arising when phonons are coupled to the electromagnetic waves in multilayered structures of nonlinear materials. The calculations are applied to a multilayered structure consisting of a thin film surrounded by semi-infinite bounding media where each layer may have a frequency dependent dielectric function and ...

Spectroscopic studies, phonon dispersion and heat capacity of poly (vinylidene chloride)

A B INITIO CALCULATION OF THE KC1 PHONON FREQUENCIES

We have calculated the phonon frequencies of KC1 along symmetry directions using an approach which is a combination of the frozen phonon and force constants methods. We also calculated Griineisen parameters for all modes at X and L points in the Brillouin zone. Finally, the slope of acoustic dispersion curves around zone center were used to calculate the three independent elastic coefficien...

بررسی ابتدا به ساکن خواص مکانیکی و گرمایی نانولوله‌های GaN با استفاده از محاسبات فونونی

In this work, we calculated the phonon dispersion of GaNNTs (4,0) and (4,4) by quantum ESPRESSO package using Density Functional Theory (DFT), pseudo potentials, and plane wave self-consistent field (PWscf) method. For the purpose of lattice-dynamical calculation and phononic properties, we used PWscf and Phonon codes. The former produces the self-consistent electronic and all related computati...

The α–β phase transition in volcanic cristobalite

Cristobalite is a common mineral in volcanic ash produced from dome-forming eruptions. Assessment of the respiratory hazard posed by volcanic ash requires understanding the nature of the cristobalite it contains. Volcanic cristobalite contains coupled substitutions of Al3+ and Na+ for Si4+; similar co-substitutions in synthetic cristobalite are known to modify the crystal structure, affecting t...