Comparison is made between a combined quantum mechanics/interatomic potential function approach ~QM-Pot! and its fully quantum-mechanical limit, ab initio calculation applying periodic boundary conditions. The Hartree–Fock ~HF! method is combined with ab initio-parametrized ion pair shell model potential functions. The CRYSTAL code is employed for the periodic Hartree–Fock calculations. The sam...

-The chemical and the mineralogical composition of a group of pumiceous tufts associated with recent salic volcanic episodes from Tenerife (Canary Islands) have been studied. The investigation focused on the two main types of pyroclastic deposits of the zone: ash-flows and ash-falls. The samples can be classified chemically as trachytic and phonolitic rocks with an intermediate silica content a...

This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This study also examined the progressive changes in the pore structures of the FSW and SSW samples over time. The res...

A first-principles microkinetic model is developed to investigate the low-temperature ammonia-assisted selective catalytic reduction (NH3-SCR) of NO over Cu-chabazite (Cu-CHA). The reaction proceeds NH3-solvated Cu sites by formation H2NNO and HONO, which decompose N2 H2O Brønsted acid sites. Nonselective N2O considered decomposition adsorption NH3 at oxidized found inhibit low temperatures hin...

The Al siting in the ZSM-5 zeolite was investigated by Al 3Q MAS NMR spectroscopy and QM/MM calculations. It was found that the occupation of the framework T-sites by Al and the concentration of Al in these T-sites are neither random nor controlled by a simple rule. They both depend on the conditions of the zeolite synthesis. At least 12 out of the 24 distinguishable framework T-sites of ZSM-5 ...