EPolyScat is a suite of FORTRAN 90 programs and libraries
that can be used to study
electron-molecule scattering processes. This includes both scattering of electrons from
neutral and ionic molecules and molecular photoionization. The current version of the
codes only treats single electronic states using a several different optical potentials
to represent the interaction between the electron and the molecule. The primary potential is
the static-exchange correlation-polarization (SECP) potential. The program can also treat
positron-molecule scattering using a selection of model local potentials.
The codes have been developed as a collaboration of the groups of Lucchese and Gianturco
beginning in 1993. The primary references for the development of the numerical methods used are given below
in the bibliography.
A given calculation uses a series of independent
that exchange information through
formatted text files. The full calculation can then be obtained through an appropriate c-shell
script that runs all the required programs. To assist in the construction of the appropriate run script
there is a script
which creates scratch directories and defines a number of
through the alias mechanism of the c-shell. These commands then invoke the various programs
with the appropriate input variables. To transfer data to the programs, there is a single
which contains labeled data records that are then read by the programs and commands as needed. There are also commands
to add and delete data from the data file. In order to run correctly, there are a few c-shell
which must also be defined.
Finally, there are a number of
which illustrate how the EPolyScat suite can be run.
In the root directory of the EPolyScat programs are the following
- contains script files that define commands, compile programs,
transfer the programs over the network, and make the HTML manual.
- contains some precalculated b_(lm)s (for Td, Oh, Ih).
- contains fortran source files.
- contains standard tests.
The following terms are are used repeatedly in the pages of this manual and are defined
for the purposes of these programs as follows:
- the expansion coefficients of the symmetry adapted harmonics in the basis set of the
real harmonics. These are described in detail in
S. L. Altmann, "On the symmetries of spherical harmonics,"
Proc. Cambridge Phil. Soc. 53 (Part 2),
- Component of an IR
- the basis function of the irreducible representation,
This is represented by an integer.
- Data file
- this is a file (fixed to be fort.95) that contains a series of data records
that are used to control the calculation and to pass data from one program to the next.
- Data record
- a single group of data that are given a symbolic label. The format is described
in detail in the description of the
command. These recodrs are processed using unformatted FORTRAN reads.
- Initial state
- in a photoionization calculation, the initial state is the
unionized bound state.
- irreducible representation, for each point group the various IRs are
represented by either an integer or a five character string.
- Multiread data record
- a data record that is read using more than one unformatted FORTRAN
read statements and thus must be represented by more than one line in the data file.
- Orbital group
- consists of the a set of degenerate molecular orbitals. If
an orbital is nondegenerate then its orbital group just contains
one orbital. For degenerate orbitals, the number of orbitals in the
group is the dimension of the IR which the orbitals transform as.
The members of the group are then indexed the the same manner as the
components of the IR. All of the input in the program are in terms of
orbital groups. For example, one specifies the number of orbital groups
and the occupations of each orbital group.
- Spin degeneracy
- an integer that gives the spin degeneracy of a particular state, i.e.
1 for a singlet, 2 for a doublet, etc.
- Symmetry type
- the full specification of the symmetry of an object including the IR it transforms
as and the component of that IR. This is represented as either a character string
(LEN = 7) or and an integer which indexes the IR and component in a single
list containing all IRs and their components.
- Target state
- the bound state that the electron scatters from.
In a photoionization calculation of a neutral molecule, this is
the ionized state after the photoelectron has left the system.
- Total scattering state
- the combined scattering state including the target
state and the continuum electron.
- F. A. Gianturco, R. R. Lucchese, N. Sanna, and A. Talamo, A Generalized
Single Center Approach for Treating Electron Scattering from Polyatomic
Molecules, in Electron Collisions with Molecules, Clusters, and Surfaces,
edited by H. Ehrhardt and L. A. Morgan, (Plenum, New York, 1994) pp. 71-86.
- F. A. Gianturco, R. R. Lucchese, and N. Sanna, On the Scattering of Low-Energy
Electrons by Sulphur Hexafluoride, J. Chem. Phys. 102, 5743-5751 (1995).
- Robert R. Lucchese and F. A. Gianturco, One-Electron Resonances in
Electron Scattering from Polyatomic Molecules, Intern. Rev. Phys. Chem. 15, 429-466 (1996).
- F. A. Gianturco and Robert R. Lucchese, One-Electron
Resonances and Computed Cross Sections in Electron Scattering
from the Benzene Molecule, J. Chem. Phys. 108, 6144-6159 (1998).
- F. A. Gianturco, R. R. Lucchese, and N. Sanna, Computed
elastic cross sections and angular distributions of
low-energy electron scattering from gas phase C60 fullerene,
J. Phys. B 32, 2181-2193 (1999).
- Alexandra P. P. Natalense and Robert R. Lucchese,
Cross section and asymmetry parameter calculation for
sulfur 1s photoionization of SF6,
J. Chem. Phys. 111, 5344-5348 (1999); Erratum, J. Chem. Phys. 112, 501 (2000).
- F. A. Gianturco and Robert R. Lucchese, One-particle resonances in low-energy
electron scattering from C60, J. Chem. Phys. 111, 6769-6786 (1999).
- F. A. Gianturco and Robert R. Lucchese, A computational
investigation of positron scattering from C60, Phys. Rev. A 60, 4567-4576 (1999).
- F. A. Gianturco and R. R. Lucchese, Electron scattering from
gaseous SF6: Comparing calculations with experiments, J. Chem. Phys. 114, 3429-3439 (2001).