Relativistic dipole matrix elements (alpha form) are calculated using atomic core and normalized continuum wavefunctions. Polarization dependence is optionally incorporated in the dipole-operator. Scattering phase shifts are determined by matching at the muffin-tin radius. Additionally, -projected density of states can be calculated in this module, but it is of limited quality due to finite cluster calculations and neglect of nonspherical corrections.
ELLIPTICITY ellipticity x y z (Useful)
This card is used with the POLARIZATION card (see below). The ellipticity is the ratio of amplitudes of electric field in the two orthogonal directions of elliptically polarized light. Only the absolute value of the ratio is important for nonmagnetic materials. The present code cannot distinguish left and right circular polarization. A zero value of the ellipticity corresponds to linear polarization, and unity to circular polarization. The default value is zero.
* circular polarization about the z-axis ELLIPTICITY 1.0 0.0 0.0 -2.0
This card specifies the direction of the electric field of the incident beam or the main axis of the ellipse in the case of elliptical polarization. x, y, z are the coordinates of the nonzero polarization vector. The ELLIPTICITY card is not needed for linear polarization. If the POLARIZATION card is omitted, spherically averaged xafs will be calculated.
POLARIZATION 1.0 2.5 0.0
EXAFS [xkmax] (Standard)
LDOS emin emax eimag (Useful)
* emin emax eimag LDOS -20 20 0.2
XANES [xkmax xkstep estep] (Standard)
The XANES card is used when a calculation of the near edge structure including the atomic background and absolute energies are desired.
The XANES calculation is currently limited to the (extended) continuum spectrum beyond the Fermi level. Thus bound states are not generally included; however, in molecules weakly bound states that are below the vacuum but above the muffin-tin zero will show up as resonances. The absolute energies are based on atomic total energy calculations using the Dirac-Fock-Desclaux atom code. The accuracy of this approximation varies from a few eV at low Z to a few hundred eV for very large Z. All parameters are optional. Default: XANES not calculated unless card is present.
The optional parameters are used to change the output energy mesh for the XANES calculation. xkstep specifies the size of the output k grid far from the edge. xkmax is the maximum k value of the XANES calculation. FMS calculations are are not accurate beyond about k=6; for larger values of k, e.g. k=20 with the path expansion, FMS must be turned off. The grid at the edge will be regular in energy with a step size of estep. The default values are , , and , where vi0 is given by the EXCHANGE card described in Section 2.3.
* finer grid for XANES calculation XANES 6. .05 .3
If this card is present, real phase shifts rather than complex phase shifts will be used. The results of the calculation will not be accurate. This option is intended to allow users to obtain real scattering phase shifts for use with other programs, or for diagnostic purposes. The phase shifts can be written to output files 'phaseNN.dat' using the PRINT card. If the RPHASES card is present, these will be the real phase shifts.