The CHSSI CCM6 Tight-Binding Module
The Tight-Binding Module of CCM6 is an extension of the CHSSI
CCM3 project, DoD-Parallel
Tight-Binding Molecular Dynamics.
Specifically, CCM6 was charged with developing
- a tight-binding method with self-consistent charge transfer
and
- the development of a library of binary alloy
parameters for studying the behavior of two-component systems,
plus some ternary parameters
In addition, we have now included a method for studying magnetic
systems by include spin polarized parameters and adding the
spin polarization-handling in the tight-binding codes
Components of the Tight-Binding Module
The tight-binding module contains several components:
- Tight-Binding Parameters for the
Elements (initially developed under CCM3)
- Binary Alloy
Parameters
- A fitting
code, for mapping the results of first-principles calculations
to our tight-binding parameters (initially developed under CCM3,
extended to binary and magnetic systems under CCM6)
- The static
code, for evaluating total energies, electronic structure, and
properties derived from this output. (initially developed under
CCM3, extended to binary and magnetic systems under CCM6)
- The Tight-Binding
Molecular Dynamics (TBMD) code, for determining total energies,
velocities, and forces on systems containing tens to thousands of
atoms. Again, the output can be used to derive various physical
properties. (Originally developed for CCM3, multi-component systems
and limited charge transfer capability added for CCM6.)
- SCTB, a charge
self-consistent tight-binding total energy evaluation code,
which includes full charge transfer capability.
Tight-Binding Theory
The theory behind the tight-binding model extensively described
in our publications. However, we recommend
the following starting points:
- R. E. Cohen, M. J. Mehl and D. A. Papaconstantopoulos, Tight-binding
total-energy method for transition and noble metals,
Phys. Rev. B 50, 14694 (1994)
- M. J. Mehl and D. A. Papaconstantopoulos, Applications
of a new tight-binding total energy method for transition and noble
metals: Elastic Constants, Vacancies, and Surfaces of Monatomic
Metals, Phys. Rev. B 54, 4519 (1996)
- M. J. Mehl and D. A. Papaconstantopoulos, Tight-Binding
Parametrization of First-Principles Results, in Topics in
Computational Materials Science, C. Y. Fong, ed. (World
Scientific, Singapore, 1998) Ch. V, pp. 169-213 (Review Article)
- N. C. Bacalis, D. A. Papaconstantopoulos, M. J. Mehl, and
M. Lach-hab, Transferable
tight binding parameters for ferromagnetic and paramagnetic
iron, Physica B 296, 125 (2001) [Magnetic
Properties]
- S. H. Yang, M. J. Mehl, D. A. Papaconstantopoulos and
M. B. Scott, Application
of a tight-binding total-energy method for FeAl, J. Phys.:
Cond. Matt. 14, 1895-1902 (2002) [A description of the
binary parameter method]
- N. Bernstein, M. J. Mehl, and D. A. Papaconstantopoulos,
Nonorthogonal tight-binding model for germanium, submitted for
publication [A description of the Charge Transfer formalism]
Section 2.1.1 of the Revised
CCM6 Report to the External Reviewers describes the tests
conducted on the TB module the CCM-6 Operational Test Readiness
Review (OTRR). It serves as a useful description of the
capabilities of the code. In particular, users are advised to study
Table 1 of this report, which shows the performance of the TBMD code as a function of system size on various
platforms.
It should be noted that performance is highly
dependent upon the number of atoms in the system and the platform,
and that, on a given platform, there is an optimal number of
processors to be used for a given number of atoms.
We have a number of publications which describe applications of
the tight-binding method. These include
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