Diffusion Monte Carlo evaluation of disiloxane linearisation barrier.

The disiloxane molecule is a prime example of silicate compounds containing the Si-O-Si bridge. The molecule is of significant interest within the field of quantum chemistry, owing to the difficulty in theoretically predicting its properties. Herein, the linearisation barrier of disiloxane is investigated using a fixed-node diffusion Monte Carlo (FNDMC) approach, which is one of the most reliable ab initio methods in accounting for the electronic correlation. Calculations utilizing the density functional theory (DFT) and the coupled cluster method with single and double substitutions, including noniterative triples (CCSD(T)) are carried out alongside FNDMC for comparison. It is concluded that FNDMC successfully predicts the disiloxane linearisation barrier and does not depend on the completeness of the basis-set as much as DFT or CCSD(T), thus establishing its suitability.

New layered perovskite family built from [CeTa2O7]- layers: coloring mechanism from unique multi-transitions.

A Ce3+-based layered perovskite compound, Dion-Jacobson type RbCeTa2O7, has been discovered for the first time by introducing only a trivalent cerium ion to form [CeTa2O7]- layers. The unique green color was experimentally and theoretically ascribed to two charge transfer transitions of ligand-to-metal O2p → Ce4f and metal-to-metal Ce4f → Ta5d.