8 results match your criteria: "Universitetsky Prosp.[Affiliation]"

Theoretical Study of α-V2O5 -Based Double-Wall Nanotubes.

Chemphyschem

October 2015

Department of Quantum Chemistry, St. Petersburg State University, Universitetsky Prosp. 26, 198504, St. Petersburg, Petergof (Russia).

First-principles calculations of the atomic and electronic structure of double-wall nanotubes (DWNTs) of α-V2 O5 are performed. Relaxation of the DWNT structure leads to the formation of two types of local regions: 1) bulk-type regions and 2) puckering regions. Calculated total density of states (DOS) of DWNTs considerably differ from that of single-wall nanotubes and the single layer, as well as from the DOS of the bulk and double layer.

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Quantum Chemical Study of Water Adsorption on the Surfaces of SrTiO3 Nanotubes.

Chemphyschem

July 2015

Quantum Chemistry Department, Saint-Petersburg State University, Universitetsky Prosp. 26, Petergof, St. Petersburg, 198504 (Russia).

We have studied the adsorption of water molecules on the inner and outer surfaces of nanotubes generated by rolling (001) layers of SrTiO3 cubic crystals. The stability and the atomic and electronic structures of the adsorbed layers are determined by using hybrid density functional theory. The absorption energy and the preferred adsorbate structure are essentially governed by the nature of the surface of the nanotube.

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The strong specific effect of coions on micellar growth from molecular-thermodynamic theory.

Phys Chem Chem Phys

September 2014

Institute of Chemistry, St.Petersburg State University, Universitetsky prosp., 26, St. Petersburg, 198504 Russia.

Viscoelastic solutions of ionic surfactants with an added salt exhibit a surprisingly strong dependence of their behavior on the nature of the added coion. We apply a recently proposed molecular-thermodynamic model to elucidate the effect of a coion's specificity on the aggregation of cationic and anionic surfactants. We show that micellar growth and branching are opposed by penetration of coions inside a micelle's corona leading to an increase of the aggregate's preferential curvature.

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Screening properties of four mesoscale smoothed charge models, with application to dissipative particle dynamics.

J Chem Phys

February 2014

Department of Chemistry, St. Petersburg State University, 26 Universitetsky prosp., 198504 St. Petersburg, Russia.

We extend our previous study [J. Chem. Phys.

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TiS2 and ZrS2 single- and double-wall nanotubes: first-principles study.

J Comput Chem

February 2014

Department of Chemistry, Quantum Chemistry Division, St. Petersburg State University, Universitetsky Prosp. 26, 198504, St. Petersburg, Petergof, Russia.

Hybrid density functional theory has been applied for investigations of the electronic and atomic structure of bulk phases, nanolayers, and nanotubes based on titanium and zirconium disulfides. Calculations have been performed on the basis of the localized atomic functions by means of the CRYSTAL-2009 computer code. The full optimization of all atomic positions in the regarded systems has been made to study the atomic relaxation and to determine the most favorable structures.

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BaTiO3-based nanolayers and nanotubes: first-principles calculations.

J Comput Chem

January 2013

Department of Chemistry, Quantum Chemistry Division, St. Petersburg State University, Universitetsky Prosp. 26, St. Petersburg 198504, Petergof, Russia.

The first-principles calculations using hybrid exchange-correlation functional and localized atomic basis set are performed for BaTiO(3) (BTO) nanolayers and nanotubes (NTs) with the structure optimization. Both the cubic and the ferroelectric BTO phases are used for the nanolayers and NTs modeling. It follows from the calculations that nanolayers of the different ferroelectric BTO phases have the practically identical surface energies and are more stable than nanolayers of the cubic phase.

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First-principles calculations on the four phases of BaTiO3.

J Comput Chem

April 2012

Department of Chemistry, Quantum Chemistry Division, St. Petersburg University, Universitetsky Prosp. 26, 198504 St. Petersburg, Petergof, Russia.

The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques.

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For a solution of the diblock copolymer composed of a hydrophobic block and a weak polyelectrolyte block, we obtain regions of stable aggregate morphologies in pH-solution salinity plane with the aid of the self-consistent field theory in the strong-segregation approximation. Lamellar, cylindrical, branched cylindrical, and spherical aggregates have been considered in the large interval of pH and salinity. The morphology stability maps are obtained to help control self-assembly of aggregates by variation of pH and salinity of the medium.

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