arXiv subjects

J. J. Fernandez

Publications and source records attributed to J. J. Fernandez.

3 recordsLinked to original sources

arXiv2019

Maximum power of a two-dimensional quantum mechanical engine with spherical symmetry

We study two-dimensional quantum Carnot engines of spherical symmetry by considering the case of a particle on the surface of a sphere of changing radius. The Carnot cycle is built allowing the state of the system to change with the specific constrains discussed in Bender's work for Carnot cycles. After studying the Carnot cycle, we maximize the output power and efficiency of the system to show that as it happens in one dimension systems:(i) the efficiency can be optimized; being its optimal value independent of the parameters describing the system and that the optimal output power at the optimal efficiency is non-zero. (ii) The optimal efficiency of the spherical system is much bigger than that of the one-dimensional quantum well considered in Abe's work.

cond-mat.stat-mech↗

arXiv2015

Contractions from $osp(1|32) \oplus osp(1|32)$ to the M-theory superalgebra extended by additional fermionic generators

We study here the generalized Weimar-Woods contractions of the superalgebra $osp(1|32) \oplus osp(1|32)$ in order to obtain a suitable algebra that could describe the gauge group of $D=11$ supergravity. The contracted superalgebras are assumed to be given in terms of fermionic extensions of the M-theory superalgebra. We show that the only superalgebra of this type obtained by contraction is the only one for which the three-form of $D=11$ supergravity cannot be trivialized. Therefore, $D=11$ supergravity cannot be connected in this way with a contraction of $osp(1|32) \oplus osp(1|32)$.

hep-th↗

arXiv2011

OEP calculations using Slater-type basis functions: atoms and diatomic molecules

The exchange-only optimized effective potential method is implemented with the use of Slater-type basis functions, seeking for an alternative to the standard methods of solution with some computational advantages. This procedure has been tested in a small group of closed shell atoms and diatomic molecules, for which numerical solutions are available. The results obtained with this implementation have been compared to the exact numerical solutions and to the results obtained when the optimized effective equations are solved using the Gaussian-type basis sets. This Slater-type basis approach leads to a more compact expansion space for representing the potential of the optimized effective method and to considerable computational savings when compared to both the numerical solution and the more traditional one in terms of the Gaussian basis sets.

physics.chem-ph↗