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Eugene V. Kholopov

Publications and source records attributed to Eugene V. Kholopov.

7 recordsLinked to original sources

Topological quantum correction to an atomic ideal gas law as a dark energy effect

The traditional ambiguity about the bulk electrostatic potentials in crystals is due to the conditional convergence of Coulomb series. The classical Ewald approach turns out to be the first one resolving this task as consistent with a translational symmetry. The latter result appears to be directly associated with the thermodynamic limit in crystals. In this case the solution can also be obtained upon direct lattice summation, but after subtracting the mean Bethe potential. As shown, this effect is associated with special periodic boundary conditions at infinity so as to neutralize an arbitrary choice of the unit-cell charge distribution. However, the fact that any additional potential exerted by some charge distribution must in turn affect that charge distribution in equilibrium is not discussed in the case at hand so far. Here we show that in the simplest event of gaseous atomic hydrogen as an example, the self-consistent mean-field-potential correction results in an additional pressure contribution to an ideal gas law. As a result, the corresponding correction to the sound velocity arises. Moreover, if gas in question is not bounded by any fixed volume, then some acceleration within that medium is expected. Addressed to the Friedman hypersphere, our result may be interesting in connection with the accelerating Universe revealed experimentally and discussed intensively.

cond-mat.other↗

Convergence peculiarities of lattice summation upon multiple charge spreading generalizing the Bertaut approach

Within investigating the multiple charge spreading generalizing the Bertaut approach, a set of confined spreading functions with a polynomial behaviour, but defined so as to enhance the rate of convergence of Coulomb series even upon a single spreading, is proposed. It is shown that multiple spreading is ultimately effective especially in the case when the spreading functions of neighbouring point charges overlap. In the cases of a simple exponential and a Gaussian spreading functions the effect of multiplicity of spreading on the rate of convergence is discussed along with an additional optimization of the spreading parameter in dependence on the cut-off parameters of lattice summation. All the effects are demonstrated on a simple model NaCl structure.

cond-mat.stat-mech↗

Spherical spin-orientation degeneracy of basic antiferromagnetic configurations due to the dipolar interaction in cubic lattices

Based on a simple general relation for the Lorentz field, the precise values are obtained for the energies of ferromagnetic and basic antiferromagnetic states in sc, bcc, fcc, and diamond cubic lattices. Within both the 'nearest-neighbor' and group-theoretic approaches, a large variety of antiferromagnetic states revealed as corresponding to the lowest energies is addressed, with recognizing their spherical spin-orientation degeneracy, which turns out to be rather special in fcc lattices.

cond-mat.mtrl-sci↗

Pyroelectric vector and related polarization effects

The principal fact that the pyroelectric vector $\Pb^0$ typical of polar crystals is invisible in equilibrium has been verified. Nevertheless, the general formula for $\Pb^0$ as a definite bulk quantity associated only with the inversion properties of a given charge distribution in the bulk has been obtained. Its application to ferroelectric perovskites BaTiO$_3$, PbTiO$_3$, and KNbO$_3$ is discussed.

cond-mat.mtrl-sci↗

Local lattice potentials and steady-state vacancies in ionic crystals

Basing on peculiarities of local potentials, the two principal trends in vacancy formation are revealed. The proximity to the threshold of local ionic stability due to a giant potential contribution of electronic delocalization accounts for thermal anion vacancies typical of intrinsic semiconductors of AB type. On the other hand, the tendency towards equalizing the potential field results in a high concentration of structural cation vacancies observed in Ni_3 Sb and relative compounds.

cond-mat.mtrl-sci↗

Translational invariance of Coulomb series and symmetric potentials in crystals

It is shown that Coulomb series are to be considered within a special mode of summation so as to describe bulk properties of crystals. The translational invariance is then an explicit integral property of Coulomb series that is tantamount to the effect of invariant periodic boundary conditions discussed earlier. Absolute bulk potentials with zero mean value are then substantiated as a unique solution in the general case of triclinic lattices. An invariant treatment of the bulk Coulomb energy follows therefrom. The potential symmetry is verified for simple point-charge lattices and is connected with the centre of gravity of the potential field that is relevant to non-local charges as well.

cond-mat.soft↗

Crystal potentials under invariant periodic boundary conditions at infinity

The definiteness of bulk electrostatic potentials in solids under periodic boundary conditions defined in an invariant manner has been proved in the general case of triclinic symmetry. Some principal consequences following from the universal potential correction arising are discussed briefly.

cond-mat.soft↗