PROGRAM SUMMARY
Title of program:
TMAT
Catalogue identifier:
ADOT
Ref. in CPC:
138(2001)281
Distribution format: gzip file
Operating system: Digital UNIX V5.0
High speed store required:
32MK words
Number of bits in a word:
64
Number of lines in distributed program, including test data, etc:
2746
Keywords:
Solid state physics, LEED, Low-Energy Electron Diffraction,
Anisotropic/anharmonic vibrations, Full dynamical theories,
Multiple scattering calculations, T-matrix (expansions in
cumulants or multipoles).
Programming language used: Fortran
Computer:
Alpha ev6-21264(700Mhz) .
Nature of problem:
We describe the FORTRAN-90 program TMAT v1.1 for the computation of
non-diagonal t-matrices representing anisotropic and/or anharmonic
atomic vibrations. TMAT can be integrated easily in any standard
Low-Energy Electron Diffraction program.
Method of solution:
The vibration of atoms in an anisotropic and/or anharmonic potential is
described by a probability distribution function. By expanding this
probability distribution function either in cumulants or in multipoles
we compute a scattering t-matrix that represents the effects of thermal
vibrations, static disorder and/or anharmonicity in the scattering of
electrons by atoms.
Typical running time:
Using the cumulants method, a single energy takes 2.5 seconds for lmax =
9. Running time scales with lmax^6.
References:
[1] J.B. Pendry, Low-Energy Electron Diffraction, (Academic, 1974). [2] V. Fritzsche, Phys. Rev. B 50, 1922 (1994). [3] W. Moritz, J. Landskron, Surf. Sci. 337, 278 (1995).