НАПРЯЖЕННОСТЬ ЭЛЕКТРИЧЕСКОГО ПОЛЯ В БАРЬЕРНОМ СЛОЕ ПОРИСТОГО ОКСИДА АЛЮМИНИЯ ПРИ АНОДИРОВАНИИ

The electric field strength calculations inside porous alumina barrier layer during electrochemical anodizing in aqueous solutions of oxalic acid at a forming voltage of 90 to 250 V have been performed. The configuration of porous alumina cells with a porosity from 1 to 10 % have been used as the input data for calculations. It is found that the value of electric field strength inside porous alumina reaches 1010-1011 V/m. New phenomena and effects, appeared during alumina anodizing process with high forming voltages, have been analyzed.Представлены результаты расчета электрического поля в пористом оксиде алюминия при электрохимическом анодировании в электролитах на основе водных растворов щавелевой кислоты при напряжениях от 90 до 250 В. Для расчета использовались конфигурации ячеек пористых оксидов алюминия с пористостью от 1 до 10 %. Рассмотрены новые явления и эффекты, возникающие в процессе пористого анодирования алюминия при высоких напряжениях, когда напряженность электрического поля внутри пористого оксида алюминия достигает величин 1010-1011 В/м

Excited-State Electronic Structure with Configuration Interaction Singles and Tamm–Dancoff Time-Dependent Density Functional Theory on Graphical Processing Units

Excited-state calculations are implemented in a development version of the GPU-based TeraChem software package using the configuration interaction singles (CIS) and adiabatic linear response Tamm–Dancoff time-dependent density functional theory (TDA-TDDFT) methods. The speedup of the CIS and TDDFT methods using GPU-based electron repulsion integrals and density functional quadrature integration allows full ab initio excited-state calculations on molecules of unprecedented size. CIS/6-31G and TD-BLYP/6-31G benchmark timings are presented for a range of systems, including four generations of oligothiophene dendrimers, photoactive yellow protein (PYP), and the PYP chromophore solvated with 900 quantum mechanical water molecules. The effects of double and single precision integration are discussed, and mixed precision GPU integration is shown to give extremely good numerical accuracy for both CIS and TDDFT excitation energies (excitation energies within 0.0005 eV of extended double precision CPU results)

Investigation of properties of nitride and silicon oxide films grown by plasma-chemical deposition on a silicon substrate

The research has been carried out on dependence of mechanical stress on the modes of deposition of silicon nitride and oxide films obtained by plasma excited chemical vapour deposition of the layers from the gas phase (PECVD). The connection has been determined between the key parameters of the deposition, such as operating pressure in the chamber, working gas consumption, deposition rate and the level of internal mechanical stresses

Analytical Gradients of Hartree-Fock Exchange with Density Fitting Approximations

We extend the local exchange (LK) algorithm [Aquilante, F.; Pedersen, T. B.; Lindh, R. J. Chem. Phys. 2007, 126, 194106] to the calculation of analytical gradients with density fitting. We discuss the features of the screening procedure and demonstrate the possible advantages of using this formulation, which is easily interfaced to a standard integral-direct gradient code. With auxiliary basis sets obtained from Cholesky decomposition of atomic or molecular integral blocks with a decomposition threshold of 10(-4)E(h), typical errors due to the density fitting in bond lengths, bond angles, and dihedral angles are 0.1 pm, 0.1 degrees, and 0.5 degrees, respectively. The overall speedup of geometry optimizations is about 1 order of magnitude for atomic natural-orbital-type basis sets but much less pronounced for correlation-consistent basis sets