arXiv subjects

D. J. Wallace Geldart

Publications and source records attributed to D. J. Wallace Geldart.

3 recordsLinked to original sources

arXiv2009

The Finite Difference Time Domain Method for Computing Single-Particle Density Matrix

A general method for numerical computation of the thermal density matrix of a single-particle quantum system is presented. The Schrodinger equation in imaginary time tau is solved numerically by the finite difference time domain (FDTD) method using a set of initial wave functions at tau=0 . By choosing this initial set appropriately, the set of wave functions generated by the FDTD method can be used to construct the thermal density matrix. The theoretical basis of the method, a numerical algorithm for its implementation, and illustrative examples in one, two and three dimensions are given in this paper. The numerical results show that the procedure is efficient and accurately determines the density matrix and thermodynamic properties of single-particle systems. Extensions of the method to more general cases are briefly indicated.

physics.comp-ph↗

arXiv2008

Interaction between a Water Molecule and a Graphite Surface

The interaction energy between a water molecule and graphitic structured clusters terminated by hydrogen atoms is analyzed by ab initio methods and decomposed into electrostatic, induction, Pauli repulsion, and correlation energy contributions. Contributions to the energy which are due solely to the perimeter of the clusters are identified. These can be isolated and discarded which greatly simplifies the problem of extrapolation to the large cluster limit. The remaining terms are intrinsic to the interaction of a water molecule with real graphitic layers and an explicit analytical form is given for the potential energy surface. The minimum energy configuration is found to have both hydrogen atoms of the water molecule pointing symmetrically away from the graphitic plane. The electronic interaction in this mode is -16.8 +/- 1.7 kJ/mol for water-graphite and the zero point energy is estimated as 1.3 kJ/mol.

physics.comp-ph↗

arXiv2007

Solving the Schrodinger Equation for a Charged Particle in a Magnetic Field using the Finite Difference Time Domain Method

We extend our finite difference time domain method for numerical solution of the Schrodinger equation to cases where eigenfunctions are complex-valued. Illustrative numerical results for an electron in two dimensions, subject to a confining potential V(x,y), in a constant perpendicular magnetic field demonstrate the accuracy of the method.

physics.comp-ph↗