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PACKAGE DESCRIPTION

TOSCA is a package for computing optical spectra of solids in the IP-RPA approximation. The full power of TOSCA is revealed when studying complex systems like surfaces or clusters.

The kernel of TOSCA is formed by a set of fortran routines that allow an ab initio non-SCF calculation by diagonalizing the Kohn-Sham hamiltonian using one of the following methods: full or partial diagonalization, diagonalization using the method of Lanczos, and Arnoldi diagonalization.

Once the eigenvalues and eigenvectors have been computed the following quantities can be computed by TOSCA:

1) Slab polarizability computed with or without real space cutoff, for insulators, semiconductors, metals. Surface epsilon can be also computed;

2) Localization of the wavefunctions for given k-point(s) and states;

3) Squared modulus of a wavefunction for a given k-point and state on the real space FFT grid. Interface with DataExplorer for graphical representation by isosurfaces;

4) RAS (Reflectance Anisotropy Spectra) or SDR (Surface Differential Reflectivity).

TOSCA is interfaced in input with a local Car-Parinnello type code and with ABINIT, by reading the wavefunctions outputed by these codes. TOSCA can also output a Kohn-Sham structure file that can be used as input for an abinitio multipurpose Many-Body code SELF.

TOSCA contains 190 fortran routines. Routines are mainly written in f77. f90 routines assure the interfacing with other ab initio codes (ABINIT, ...).


next up previous
Next: TOSCA's GUIDE Up: userguide Previous: userguide
Andrei Incze 2005-06-29