81 lines
3.3 KiB
Plaintext
81 lines
3.3 KiB
Plaintext
The files in this directory are a user-contributed package for LAMMPS.
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The person who created these files is Andres Jaramillo-Botero at
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CalTech (ajaramil@wag.caltech.edu). Contact him directly if you have
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questions.
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--------------------------------------
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Andres Jaramillo-Botero
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California Institute of Technology (Caltech)
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Chemistry and Chemical Engineering, 139-74
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1200 E. California Blvd., Pasadena, CA 91125
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Phone: (626) 395-3591
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e-mail: ajaramil@wag.caltech.edu
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Co-Authors:
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Julius Su (jsu@wag.caltech.edu)
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William A. Goddard III (wag@wag.caltech.edu)
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PACKAGE DESCRIPTION:
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Contains a LAMMPS implementation of the electron Force Field (eFF)
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currently under development at Caltech, as described in
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A. Jaramillo-Botero, J. Su, Q. An, and W.A. Goddard III, JCC,
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2010. The eFF potential was first introduced by Su and Goddard, in
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2007.
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eFF can be viewed as an approximation to QM wave packet dynamics and
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Fermionic molecular dynamics, combining the ability of electronic
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structure methods to describe atomic structure, bonding, and chemistry
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in materials, and of plasma methods to describe nonequilibrium
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dynamics of large systems with a large number of highly excited
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electrons. We classify it as a mixed QM-classical approach rather than
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a conventional force field method, which introduces QM-based terms (a
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spin-dependent repulsion term to account for the Pauli exclusion
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principle and the electron wavefunction kinetic energy associated with
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the Heisenberg principle) that reduce, along with classical
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electrostatic terms between nuclei and electrons, to the sum of a set
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of effective pairwise potentials. This makes eFF uniquely suited to
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simulate materials over a wide range of temperatures and pressures
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where electronically excited and ionized states of matter can occur
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and coexist.
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The necessary customizations to the LAMMPS core are in place to
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enable the correct handling of explicit electron properties during
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minimization and dynamics.
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INSTALLATION:
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via a normal LAMMPS package installation: make yes-user-eff
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OTHERS FILES INCLUDED:
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User examples are under examples/USER/eff
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eFF tools are under tools/eff
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ACKNOWLEDGMENTS:
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Thanks to Steve Plimpton and Aidan Thompson for their input on the
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LAMMPS architecture and for their help in customizing some of the
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required LAMMPS core modules.
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Version 01/2010: Special thanks to:
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- Hai Xiao (Caltech) for reviewing the fixed-core implementation and
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providing useful insights to improve it, and for his work on the effective core pseudopotential.
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- Vaclav Cvicek (Caltech) for thoroughly revising the units, for finding a bug in the
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fix_langevin_eff radial scaling factors, and for suggesting changes to clean-up the code.
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- Patrick Theofanis (Caltech) for providing an optimized set of parameters for the Si ECP
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(default) and for providing basic cases.
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- Qi An (Caltech) for providing feedback on usage, application cases, and testing.
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VERSION NOTES:
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01/2010: Added support for fixed-core and effective core pseudopotentials [ECP]
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(useful for C, Al, Si, O and other elements). Cleaned up the code to make it
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easier to maintain, revised support for real units, upgraded post-processing
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and visualization tools, added support for "compute pair eff" to allow thermo
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prints with the different eFF energy components (eke, epauli, ecoul and errestrain),
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fixed radial scaling factors in the eff langevin thermostat.
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