Command Scat
Command format
Scat
Energy1 Energy2 ...
or
ScatN
EnergyStart EnergyStep NumberofEnergies
This command computes the K or T scattering matrix
for electronmolecule scattering.
The Scat
form does the calculation at
a list of scattering energies (in eV). If no energies are present then the energies are
taken from the
ScatEng,
or
ScatEngN,
data records.
The ScatN
form does the calculation at
a sequence of scattering energies with fixed spacing (in eV).
If the command
FileName
has been used to define the MatrixElements
file,
then the final K or T matrix elements
are written to the file specified there. Otherwise, the matrix elements
are written to a scratch file.
Data records used

FegeEng,
this is the value of the energy parameter (in eV) needed to compute the FEGE local exchange potential.

ScatEng,
scattering energy, in eV. This data record is not used if
Energy is defined in the Scat command.

ScatEngN,
scattering energy, in eV. This data record is not used if
Energy is defined in the Scat command.

ScatContSym,
the IR of the continuum orbital.

EngForm,
potential energy formula.
Optional data records used

FegeScale,
Optional value used to scale the local exchange potential. This can be used
to curcumvent singularities in the interative procedure.
Default value is 1.0.

GrnType,
Optional, the type of the scattering matrix (1, 0, or 1).
Default value is 0 for a T matrix calculation.

IterMax,
Optional.
Maximum number of iterations allowed in the Pade approximant
corrections of the scattering matrix elements.
Default value is 15. A value of 1 is used for a static only calculation.

LMaxEx,
Optional. maximum l used in the expansion of
1/r_12
in the exchange terms.
Default value is 1, which inclludes all exchange terms.

NIntReg,
number of regions used in stabilization.
Default value is 40.

CnvgKMat,
parameter that controls the convergence of the iterative procedure.
Default value is 1.0e6.

EpsAsym,
this data record controls where the asymptotic integration is truncated.
The default is to stop the integration when the asymptotic potential is less than
CnvgKMat/10 times the asymptotic electron kinetic energy.

TotalAsymp,
controls the form of the asymptotic potential.

Orthog,
this data record controls which orbital groups the continuum function is constrained to be
orthogonal to. This overides the orthogonality constraints specified in EngForm.

RungeKuttaFac
this integer controls the step size used in the differential equation integrator.
Higher values yields smaller step sizes.
Default value is 4..

HFacWaveAsym,
a real number that is used to generate the asymptotic radial grid. The higher the value the
more dense the grid will be between for r greater than RMax.
Default value is the value of HFacWave used to generate the grid, the default value
for that parameter is 10.

EpsIntError,
this is used as an estimate of the error in the numerical integrations. It is
used to control the convergenc of the iterative procedure.
Default value is 1.0e8.

LMaxHomo,
contains
an integer that specifies the truncation of the partial wave expansion
in the homogeneous solution of the static potential scattering.
The default value is
MAX(LMaxA, LMax/2)

LMaxK,
the maximum l used in the expansion of the
homogeneous scattering solution. This is thus the dimension of the scattering matrix.
Note that this should be greater than or equal to
LMaxA. Default value is LMaxA2.

NAsymLRange,
the range of the functions on the left of the variational expression that should be
computed. The default value is to use the full range up to NAsymL.
Examples of use

test01
K matrix form.

test04,
T matrix form.

test11,
compare K matrix and T matrix forms.

test16,
scattering from local potential only. Also compare different local exchange potentials.