Integrating the quantum HamiltonJacobi equations by wavefront expansion and phase space analysis
J. Chem. Phys. 113, 8888 (2000); doi:10.1063/1.1319987
Issue Date: 22 November 2000
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In this paper we report upon our computational methodology for numerically integrating the quantum HamiltonJacobi equations using hydrodynamic trajectories. Our method builds upon the moving least squares method developed by Lopreore and Wyatt [Phys. Rev. Lett. 82, 5190 (1999)] in which Lagrangian fluid elements representing probability volume elements of the wave function evolve under Newtonian equations of motion which include a nonlocal quantum force. This quantum force, which depends upon the third derivative of the quantum density,
, can vary rapidly in x and become singular in the presence of nodal points. Here, we present a new approach for performing quantum trajectory calculations which does not involve calculating the quantum force directly, but uses the wavefront to calculate the velocity field using mv =
S, where S/
is the argument of the wave function
. Additional numerical stability is gained by performing local gauge transformations to remove oscillatory components of the wave function. Finally, we use a dynamical RayleighRitz approach to derive ancillary equations-of-motion for the spatial derivatives of
, S, and v. The methodologies described herein dramatically improve the long time stability and accuracy of the quantum trajectory approach even in the presence of nodes. The method is applied to both barrier crossing and tunneling systems. We also compare our results to semiclassical based descriptions of barrier tunneling. ©2000 American Institute of Physics.
, can vary rapidly in x and become singular in the presence of nodal points. Here, we present a new approach for performing quantum trajectory calculations which does not involve calculating the quantum force directly, but uses the wavefront to calculate the velocity field using mv =
S, where S/
is the argument of the wave function
. Additional numerical stability is gained by performing local gauge transformations to remove oscillatory components of the wave function. Finally, we use a dynamical RayleighRitz approach to derive ancillary equations-of-motion for the spatial derivatives of
, S, and v. The methodologies described herein dramatically improve the long time stability and accuracy of the quantum trajectory approach even in the presence of nodes. The method is applied to both barrier crossing and tunneling systems. We also compare our results to semiclassical based descriptions of barrier tunneling. ©2000 American Institute of Physics.
| History: | Received 13 July 2000; accepted 1 September 2000 |
| Permalink: |
http://link.aip.org/link/?JCPSA6/113/8888/1 |
EDITORIALLY RELATED
- Quantum wave packet dynamics with trajectories: Implementation with adaptive Lagrangian grids
Robert E. Wyatt et al.
J. Chem. Phys. 113, 8898 (2000)
KEYWORDS and PACS
RELATED DATABASES
PUBLICATION DATA
0021-9606 (print)
1089-7690 (online)
REFERENCES (27)
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