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21.
F. J. Gálvez E. Buendía A. Sarsa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):161-167
Explicitly correlated wave functions including a Jastrow factor
to take into account the dynamical correlation effects, and a
multi determinant model wave function to account for the non–dynamical
correlations are used to study some metastable excited states of the
negative ions Li- and Be-.
A detailed analysis of one– and two–body properties has been carried out
for these states. In particular the single–particle density as well as both
the two–body inter electronic and center of mass densities have been obtained.
All the calculations have been performed by using the variational Monte Carlo
method. 相似文献
22.
We present diffusion quantum Monte Carlo calculations of the interchange tunneling splitting of (4)He(n)(HF)(2) clusters, n = 1-10. The tunneling splitting decreases rapidly for n = 1-4 clusters, and much more slowly for n>4. The decrease calculated for (4)He(n)(HF)(2) represents 74% of the reduction in the tunneling splitting measured recently for HF dimer in nanodroplets of more than 2000 He atoms. The first four He atoms quench the interchange tunneling very efficiently by virtue of occupying the equatorial ring which encircles the C(2h) transition state of the tunneling pathway. 相似文献
23.
The structural and dynamical properties of carbonyl sulfide (OCS) molecules solvated in helium clusters are studied using reptation quantum Monte Carlo, for cluster sizes n=3-20 He atoms. Computer simulations allow us to establish a relation between the rotational spectrum of the solvated molecule and the structure of the He solvent, and of both with the onset of superfluidity. Our results agree with a recent spectroscopic study of this system and provide a more complex and detailed microscopic picture of this system than inferred from experiments. 相似文献
24.
C. E. Aalseth F. T. Avignone III R. L. Brodzinski S. Cebrian D. Gonzáles E. García W. K. Hensley I. G. Irastorza I. V. Kirpichnikov A. A. Klimenko H. S. Miley A. Morales J. Morales A. Órtiz de Solórzano S. B. Osetrov V. S. Pogosov J. Puimedón J. H. Reeves M. L. Sarsa S. Scopel A. A. Smolnikov A. S. Starostin A. G. Tamanyan A. A. Vasenko S. I. Vasiliev J. A. Villar 《Physics of Atomic Nuclei》2000,63(7):1225-1228
The International Germanium Experiment (IGEX) has now analyzed 117 mol yr of data from its isotopically enriched (86% 76Ge) germanium detectors. Applying pulse shape discrimination (PSD) to the more recent data, the lower bound on the half-life for neutrinoless double-beta decay of 76Ge is deduced: T 1/2(0ν)>1.57×1025 yr (90% C.L.). This corresponds to an upper bound on the Majorana neutrino mass parameter, 〈m ν〉, between 0.33 eV and 1.35 eV depending on the choice of theoretical nuclear matrix elements used in the analysis. 相似文献
25.
Ekiel-Jezewska ML; Wajnryb E 《The Quarterly Journal of Mechanics and Applied Mathematics》2006,59(4):563-585
An example system is studied to discuss precision of the multipoleexpansion, applied to determine forces exerted on particlesby a viscous low-Reynolds-number fluid flow. A single spherein an ambient flow (pure shear, quadratic, and modulated shear)parallel to a close plane wall is considered. Forces and torquesexerted by the ambient flow on a motionless sphere are evaluated.Their precision is determined and related to a multipole orderof the truncation. Similar analysis is performed for a movingsphere with no ambient flow and for a freely moving sphere.Relative motion of the sphere with respect to the wall givesrise to strong lubrication interactions. It is analysed howthese interactions affect accuracy of the pure multipole expansion,and what are the smallest distances where it becomes insufficient.An alternative precise method is applied, in which lubricationexpressions are subtracted from the hydrodynamic forces andtorques, and the residue is evaluated as a fast-convergent seriesof inverse powers of the distance between the sphere centreand the wall. The accuracy of this procedure is carefully analysed. 相似文献
26.
C. E. Aalseth F. T. Avignone III R. L. Brodzinski S. Cebrian D. Gonzáles E. García W. K. Hensley I. G. Irastorza I. V. Kirpichnikov A. A. Klimenko H. S. Miley A. Morales J. Morales A. Órtiz de Solórzano S. B. Osetrov V. S. Pogosov J. Puimedón J. H. Reeves M. L. Sarsa S. Scopel A. A. Smolnikov A. S. Starostin A. G. Tamanyan A. A. Vasenko S. I. Vasiliev J. A. Villar 《Physics of Atomic Nuclei》2000,63(7):1268-1271
To search for cold dark matter (CDM) particles, the data from two (Ge-76 and Ge-natural) detectors, fabricated in the first phase of the IGEX collaboration, were accumulated and analyzed for a period from May 1995 to May 1999. The use of effective passive and active shielding together with pulse shape discrimination allowed us to perform long-term measurements with an energy threshold of 2 keV at a level of the residual background 0.1 counts/(kg keV d). New restrictions on masses of weakly interacting massive particles and the cross section of their elastic scattering on nuclei have been obtained from the data corresponding to 810 d of live time. The derived exclusion plots compete with the best bounds obtained so far. Annual modulations of the CDM signal have been also investigated. It is shown that the planned operation of all IGEX detectors (at Canfranc and Baksan) with the recently achieved low-energy thresholds gives a chance to achieve the DAMA annual modulation sensitivity region in a nearest future. 相似文献
27.
A study of different quantum similarity measures and their corresponding quantum similarity indices is carried out for the atoms from H to Lr (Z=1-103). Relativistic effects in both position and momentum spaces have been studied by comparing the relativistic values to the non-relativistic ones. We have used the atomic electron density in both position and momentum spaces obtained within relativistic and non-relativistic numerical-parameterized optimized effective potential approximations. 相似文献
28.
29.
The variational Monte Carlo method is applied to calculate ground‐state energies of some cations and anions of the first‐row atoms. Accurate values providing between 80 and 90% of the correlation energy are obtained. Explicitly correlated wave functions including up to 42 variational parameters are used. The nondynamic correlation due to the 2s ? 2p near degeneracy effect is included by using a multideterminant wave function. The variational free parameters have been fixed by minimizing the energy that has shown to be a more convenient functional than the variance of the local energy, which is the most commonly employed method in variational Monte Carlo calculations. The energies obtained improve previous works using similar wave functions. © 2002 Wiley Periodicals, Inc.; DOI 10.1002/qua.10125 相似文献
30.
F. Arias de Saavedra E. Buendıa F.J. Gálvez A. Sarsa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):201-206
A generalized Hylleraas-type basis set with three nonlinear parameters is proposed to study three-body systems interacting
via coulomb forces within the framework of non-relativistic quantum mechanics. This basis set improves the rate of convergence
with respect to previous ones, specially for non-symmetric systems and excited states of two electron atoms. Accurate binding
energies and other properties for S-states of helium-like ions, muonic molecules and the positronium negative ion are reported.
Received 21 July 2000 and Received in final form 4 October 2000 相似文献