Semi-empirical and ab initio calculations for crystals under pressure at fixed temperatures: the case of guanidinium perchlorate

A simple semi-empirical approach is proposed to calculate structure and properties of crystals under pressure at fixed temperatures. The computed semi-empirical pressure dependencies for guanidinium perchlorate are in good agreement with available experimental data. Ab initio results within quasi-harmonic approximation for guanidinium perchlorate are also presented.

Pressure-and temperature induced phase transitions, piezochromism, NLC behaviour and pressure controlled Jahn-Teller switching in a Cu-based framework

In situ single-crystal diffraction and spectroscopic techniques have been used to study a previously unreported Cu-framework bis[1-(4-pyridyl)butane-1,3-dione]copper(ii) (CuPyr-I). CuPyr-I was found to exhibit high-pressure and low-temperature phase transitions, piezochromism, negative linear compressibility, and a pressure induced Jahn–Teller switch, where the switching pressure was hydrostatic media dependent.

In situ high-pressure single-crystal diffraction and spectroscopic techniques have been used to study a previously unreported Cu-framework bis[1-(4-pyridyl)butane-1,3-dione]copper(ii) (CuPyr-I).

The nature of the chemical bond in oxyanionic crystals based on QTAIM topological analysis of electron densities

The QTAIM topological analysis of the calculated electron densities in oxyanionic crystals revealed the covalency criteria for metal–oxygen and hydrogen bonds.