Single-center method of calculation for clusters and molecules other than hydrides

Lagutin, B. M.; Migal, Yu. F.

doi:10.1007/bf00580291

Cited by 4 publications

(3 citation statements)

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“…We should note that the integral of Eq. (61) contains a serious divergence att = 0 because of the large but improbable contributions from very young and nearby sources [115,[138][139][140]. Here we follow and set the cutoff parameter aŝ…”

Section: A Electron Distribution Function From a Single Sourcementioning

confidence: 99%

White dwarf pulsars as possible cosmic ray electron-positron factories

2011

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We suggest that white dwarf (WD) pulsars can compete with neutron star (NS) pulsars for producing the excesses of cosmic ray electrons and positrons (e ± ) observed by the PAMELA, ATIC/PPB-BETS, Fermi and H.E.S.S experiments. A merger of two WDs leads to a rapidly spinning WD with a rotational energy (∼ 10 50 erg) comparable to the NS case. The birth rate (∼ 10 −2 -10 −3 /yr/galaxy) is also similar, providing the right energy budget for the cosmic ray e ± . Applying the NS theory, we suggest that the WD pulsars can in principle produce e ± up to ∼ 10 TeV. In contrast to the NS model, the adiabatic and radiative energy losses of e ± are negligible since their injection continues after the expansion of the pulsar wind nebula, and hence it is enough that a fraction ∼ 1% of WDs are magnetized (∼ 10 7 -10 9 G) as observed. The long activity also increases the number of nearby sources (∼ 100), which reduces the Poisson fluctuation in the flux. The WD pulsars could dominate the quickly cooling e ± above TeV energy as a second spectral bump or even surpass the NS pulsars in the observing energy range ∼ 10GeV-1TeV, providing a background for the dark matter signals and a nice target for the future AMS-02, CALET and CTA experiment. PACS numbers: 97.20.Rp, 98.70.Sa I. INTRODUCTIONRecently, the observational windows to the electron and positron (e ± ) cosmic rays are rapidly expanding the energy frontier, revealing new aspects of our Universe. The PAMELA satellite [1] shows that the cosmic ray positron fraction (the ratio of positrons to electrons plus positrons) rises in the energy range of 10 to 100 GeV, contrary to the theoretical prediction of secondary positrons produced by hadronic cosmic rays interacting with the interstellar medium (ISM) [110]. Shortly thereafter, ATIC/PPB-BETS [2, 3] suggest an sharp excess of the e ± with a peak at 600 GeV, and although not confirming the ATIC/PPB-BETS sharp peak spectrum 1 , Fermi [4-6] and H.E.S.S [7,8] also suggest an excess of the e ± total flux around 100 GeV -1 TeV compared to theoretical predictions based on low energy cosmic ray e ± spectrum [33,34]. All these observations of the e ± excesses probably connected with the PAMELA positron excess, and most likely suggest a new source, possibly the astrophysical accelerators or dark matter annihilation [31-33, 35-66] /decay [36,39,44,52,61,64,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83], although there might remain alternatives such as the propagation effects [89][90][91][92][93] or proton contamination [94][95][96]. These discoveries have excited the entire particle and astrophysics communities and prompted over 300 papers within a year. See [9] for a recent review.The most fascinating possibility for the e ± excesses is the dark matter, such as weakly interacting massive particles (WIMPs) that only appear beyond the Standard Model. Dark matter is a stable particle that accounts most of the matter in the Universe but the nature is not known yet. Usually, the observed e ± excesses are far larger than...

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Section: A Electron Distribution Function From a Single Sourcementioning

confidence: 99%

White dwarf pulsars as possible cosmic ray electron-positron factories

2011

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“…The method represents one-particle molecular orbitals by expansions over spherical functions with respect to a single molecular center. Traditional way of its realization is to represent partial waves via a fixed radial basis and use a variational principle to minimize the total energy of an electronic state [34,49,[59][60][61][62][63][64]. However, for photoelectron in the continuum, it is more efficient to solve an inhomogeneous system of coupled Hartree-Fock equations for the radial partial waves [35,[65][66][67][68][69][70].…”

Section: Introductionmentioning

confidence: 99%

“…However, for photoelectron in the continuum, it is more efficient to solve an inhomogeneous system of coupled Hartree-Fock equations for the radial partial waves [35,[65][66][67][68][69][70]. In the last two decades, our version of the single center method [34,49,[59][60][61][62][63][64] was considerably improved by incorporating a non-iterative scheme to account for the non-local exchange interaction [71,72] and implementing an efficient procedure for the numerical solution of the system of coupled differential equations in diatomic [36] and polyatomic [37] molecules on a radial grid. Simultaneously, a time-dependent formulation [73][74][75] of the SC method was developed.…”

Section: Introductionmentioning

confidence: 99%

Multichannel single center method

Novikovskiy

Artemyev

Rezvan

et al. 2022

J. Phys. B: At. Mol. Opt. Phys.

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Multichannel single center (MCSC) method for the theoretical description of the electron continuum spectrum in molecules is reported. The method includes coupling between different continuum channels via electron correlations and describes, thereby, photoelectron continuum in the Tamm-Dancoff (configuration interaction singles) approximation. Basic equations of the non-iterative one-channel single center (SC) method and their extension to the MCSC method are presented, and an efficient scheme for their numerical solution is outlined. The method is tested on known illustrative examples of the Ar 3s-, HCl 4σ- and N2 1σ-photoionization processes, where inter-channel coupling plays a very important role. Unlike our previous SC studies, the present MCSC method can reliably be applied to photoionization of outer and valence molecular orbitals, where inter-channel correlations in continuum might be relevant.

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