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Papers by alberto garcia
Journal of Physics-condensed Matter, 2002
We have developed and implemented a self-consistent density functional method using standard norm... more We have developed and implemented a self-consistent density functional method using standard norm-conserving pseudopotentials and a flexible, numerical LCAO basis set, which includes multiple-zeta and polarization orbitals. Exchange and correlation are treated with the local spin density or generalized gradient approximations. The basis functions and the electron density are projected on a real-space grid, in order to calculate the Hartree and exchange-correlation potentials and matrix elements, with a number of operations that scales linearly with the size of the system. We use a modified energy functional, whose minimization produces orthogonal wavefunctions and the same energy and density as the Kohn-Sham energy functional, without the need of an explicit orthogonalization. Additionally, using localized Wannier-like electron wavefunctions allows the computation time and memory, required to minimize the energy, to also scale linearly with the size of the system. Forces and stresses are also calculated efficiently and accurately, thus allowing structural relaxation and molecular dynamics simulations.
Using the Green-Kubo theory, the dependence of the viscosity and thermal conductivity on cell siz... more Using the Green-Kubo theory, the dependence of the viscosity and thermal conductivity on cell size is obtained explicitly for stochastic particle methods such as direct simulation Monte Carlo ͑DSMC͒ and its generalization, the consistent Boltzmann algorithm ͑CBA͒. These analytical results confirm empirical observations that significant errors occur when the cell dimensions are larger than a mean free path.
Page 1. COMPLTER SIMULATIONS THE DIRECT SIMULATION MONTE CARLO METHOD Francis J. Alexander and Al... more Page 1. COMPLTER SIMULATIONS THE DIRECT SIMULATION MONTE CARLO METHOD Francis J. Alexander and Alejandro L. Garcia Department Editors: Harvey Gould kgould@clarka.eei Jan Tobochnik jarit@kzoo,edu ...
Journal of Physics-condensed Matter, 2002
We have developed and implemented a self-consistent density functional method using standard norm... more We have developed and implemented a self-consistent density functional method using standard norm-conserving pseudopotentials and a flexible, numerical LCAO basis set, which includes multiple-zeta and polarization orbitals. Exchange and correlation are treated with the local spin density or generalized gradient approximations. The basis functions and the electron density are projected on a real-space grid, in order to calculate the Hartree and exchange-correlation potentials and matrix elements, with a number of operations that scales linearly with the size of the system. We use a modified energy functional, whose minimization produces orthogonal wavefunctions and the same energy and density as the Kohn-Sham energy functional, without the need of an explicit orthogonalization. Additionally, using localized Wannier-like electron wavefunctions allows the computation time and memory, required to minimize the energy, to also scale linearly with the size of the system. Forces and stresses are also calculated efficiently and accurately, thus allowing structural relaxation and molecular dynamics simulations.
Using the Green-Kubo theory, the dependence of the viscosity and thermal conductivity on cell siz... more Using the Green-Kubo theory, the dependence of the viscosity and thermal conductivity on cell size is obtained explicitly for stochastic particle methods such as direct simulation Monte Carlo ͑DSMC͒ and its generalization, the consistent Boltzmann algorithm ͑CBA͒. These analytical results confirm empirical observations that significant errors occur when the cell dimensions are larger than a mean free path.
Page 1. COMPLTER SIMULATIONS THE DIRECT SIMULATION MONTE CARLO METHOD Francis J. Alexander and Al... more Page 1. COMPLTER SIMULATIONS THE DIRECT SIMULATION MONTE CARLO METHOD Francis J. Alexander and Alejandro L. Garcia Department Editors: Harvey Gould kgould@clarka.eei Jan Tobochnik jarit@kzoo,edu ...