  FERM3D is a three-dimensional finite element program, for the elastic
scattering of a low energy electron from a general polyatomic molecule, which
is converted to a potential scattering problem. The code is based on tricubic
polynomials in spherical coordinates. The electron-molecule interaction is
treated as a sum of three terms: electrostatic, exchange. and polarisation. The
electrostatic term can be extracted directly from ab initio codes
({\sc{GAUSSIAN 98}} in the work described here), while the exchange term is
approximated using a local density functional. A local polarisation potential
based on density functional theory [C. Lee, W. Yang and R. G. Parr, {Phys. Rev.
B} {37}, (1988) 785] describes the long range attraction to the molecular
target induced by the scattering electron. Photoionisation calculations are
also possible and illustrated in the present work. The generality and
simplicity of the approach is important in extending electron-scattering
calculations to more complex targets than it is possible with other methods.
