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Alexei M Frolov

Publications and source records attributed to Alexei M Frolov.

6 recordsLinked to original sources
PubMed2006

Optimization of nonlinear parameters in trial wave functions with a very large number of terms.

A procedure is proposed to construct highly accurate variational wave functions with large and very large numbers of basis functions. The procedure has a number of advantages in actual computations on parallel computer clusters. In particular, by using this procedure we have determined very accurate numerical values of the ground-state energies in the positronium ion Ps(-) (or e(-)e(+)e(-)) (E= -0.262 005 070 232 980 107 770 375 a.u.) and hydrogen ion infinityH(-) (E= -0.527 751 016 544 377 196 589 759 a.u.) The variational energies of the negative hydrogenlike ions (or H(-)-like ions) with the finite nuclear masses (T(-), D(-), 1H(-), and Mu(-)) are also presented. These energies are the best variational ground-state energies ever obtained for these ions.

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PubMed2006

Isotopic effects for the ground 1 1S(L=0) states in the light two-electron ions.

The total energies and various bound state properties are determined to very high accuracy for the ground 1 (1)S(L=0) states in some light two-electron ions, including the Li(+), Be(2+), B(3+), and C(4+) ions. The corrections due to the finite nuclear masses and lowest order QED corrections ( approximately alpha(3)) are considered/computed for each of these ions. In particular, the specific mass shift is determined for each of the Li(+), Be(2+), B(3+), and C(4+) ions. We also discuss the field shift related to the extended nuclear charge distribution.

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PubMed2004

Singular and nonsingular three-body integrals for exponential wave functions.

Integrals which are individually singular, but which may be combined to yield convergent expressions, are needed for computations of relativistic effects and various properties of atomic and quasiatomic systems. As computations become more detailed and precise, more such integrals are required. This paper presents general formulas for the radial parts of the singular and nonsingular (regular) integrals that occur when three-body systems are described using wave functions that include exponentials in all three interparticle coordinates. Our results are compared with those found in the literature for some of the integrals, and are also shown to be consistent with previously reported results for Hylleraas functions (a limiting case in which one of the exponential parameters is set to zero).

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PubMed2004

Highly accurate evaluation of atomic three-electron integrals of lowest orders.

Calculations of three-electron atomic systems in Hylleraas coordinates require integrals involving all the interparticle distances r(ij), which have usually been evaluated by introducing series expansions. For integrals with the smallest powers of r(ij) these expansions do not converge at a satisfactory rate, leading some investigators to introduce convergence-acceleration procedures. This paper recommends the alternative of evaluating these integrals in closed form and presents stable explicit formulas for so doing. Some of the formulas are more compact versions of those in the literature; others have not been previously reported. It is also shown that finite-difference methods can be used with advantage to obtain additional low-order integrals. Sample integral values have been provided for test purposes.

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PubMed2002

Bound state properties of the ground states in the DT+ and T(2)+ ions.

Recently developed multibox approach [A.M. Frolov, Phys. Rev. E 64, 036704 (2001)] is used to construct highly accurate, bound state wave functions for the ground states in the heavy adiabatic ions DT+ and T(2)+. The computed variational energies and bound state properties have significantly higher accuracy than results known from earlier computations. Nevertheless, the computed and predicted nucleus-nucleus cusp and nucleus-nucleus delta function differ significantly even for the highly accurate wave functions used in this study.

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