Search Results (All Fields:"http://udcdata.info/027739", Keywords:"http://udcdata.info/029653", Author:"Sesé, Luis M") - e-spacio
http://e-spacio.uned.es/fez/
Universidad Nacional de Educación a DistanciaspFez 2.1 RC3http://blogs.law.harvard.edu/tech/rssPath-integral Monte Carlo and static structures in condensed matter
http://e-spacio.uned.es/fez/view/bibliuned:DptoCTFQ-FCIE-MODELICO-1020
2014-09-04T23:19:27Z
Sesé, Luis M.
Path integral Monte Carlo study of quantum-hard sphere solids
http://e-spacio.uned.es/fez/view/bibliuned:DptoCTFQ-FCIE-MODELICO-1040
A path integral study of the fcc, hcp, and bcc quantum hard-sphere solids is presented. Ranges of
densities within the interval of reduced de Broglie wavelengths 0.2 * 0.8 B ≤ λ ≤ have been
analyzed using Monte Carlo simulations with Cao-Berne propagator. Energies, pressures, and
structural quantities (pair radial correlation functions, centroid structure factors, and Steinhardt
order parameters) have been computed. Also, applications of the Einstein crystal technique (J.
Chem. Phys. 126, 164508 (2007)) have been made to compute the free energies of the fcc and
hcp solids. Some technical points related to the latter technique are discussed, and it is shown
that these calculations produce consistent results with increasing sample sizes. The fluid-solid
(fcc and hcp) equilibria have been studied, thus completing prior work by this author on the
fluid-fcc equilibrium. Within the accuracy attained no significant differences between the relative
stabilities of the fcc and hcp lattices have been detected. The bcc case stands apart from the other
two lattices, as the simulations lead either to irregular lattices (two types) that keep some traces
of bcc-memory, or to spontaneous transitions to hcp-like lattices. The latter transitions make
manifestly clear the potential repercussions that the quantum hard-sphere behavior can have on
solid-solid equilibria at low temperatures in real systems (e.g. helium).
Versión Pre-print2014-09-04T23:19:27Z
Sesé, Luis M.
On the accurate direct computation of the isothermal compressibility for
normal quantum simple fluids : application to quantum hard spheres
http://e-spacio.uned.es/fez/view/bibliuned:DptoCTFQ-FCIE-MODELICO-1035
A systematic study of the direct computation of the isothermal compressibility of normal quantum
fluids is presented by analyzing the solving of the Ornstein-Zernike integral equation (OZ2) for the
pair correlations between the path-integral necklace centroids. A number of issues related to the
accuracy that can be achieved via this sort of procedure have been addressed, paying particular
attention to the finite-N effects and to the definition of significant error bars for the estimates of
isothermal compressibilities. Extensive path-integral Monte Carlo computations for the quantum
hard-sphere fluid (QHS) have been performed in the (N,V,T) ensemble under temperature and
density conditions for which dispersion effects dominate the quantum behavior. These
computations have served to obtain the centroid correlations, which have been processed further
via the numerical solving of the OZ2 equation. To do so, Baxter-Dixon-Hutchinson’s variational
procedure complemented with Baumketner-Hiwatari’s grand-canonical corrections have been
used. The virial equation of state has also been obtained and several comparisons between different
versions of the QHS equation of state have been made. The results show the reliability of the
procedure based on isothermal compressibilities discussed herein, which can then be regarded as a
useful and quick means of obtaining the equation of state for fluids under quantum conditions
involving strong repulsive interactions.Versión Pre-print2014-09-04T23:19:27Z
Sesé, Luis M.