This project involved the calculation of the effect of compression on atomic
electronic wavefunctions, densities and energies. The compression is
achieved through a modification to the wavefunctions in a numerical
Hartree-Fock-Slater computation based on the Herman&Skillman program of
1963. As an atom is compressed the following trends are observed:
The wavefunctions tend to zero near the compression radius, and are not
well approximated with Slater type function shapes.
The electron density becomes noticably more compact and goes to zero
more sharply than in the free atom.
The energy of the highest electron increases untill it becomes positive
at a certain compression radius, which can then be defined as an
"ionization" radius.
These ionization radii have been calculated for the entire periodic table
and their periodic trends compared very favourably with many other well known
periodic properties of the elements.
The x-ray scattering factors that can be calculated for these compressed
atom electron densities show interesting features at low angles as expected,
but these features quickly become negligable as one goes to heavier atoms.
These calculations were used to generate new theoretical electron densities
for atoms in the condensed state. From these densities, x-ray scattering
factors were calculated and used in the refinement of small molecule crystal
structures. Trends were observed for the effect of compressing the atomic
models to different degrees in different crystal structures. A number of atoms,
including C, Li and B showed interesting behaviour, supporting the
proposition that atoms in the condensed state, or even the bonded state, are
better modelled through simulated compression than as free atoms.
Example Plots from Compressed Atom Calculations Clicking on an image gives a medium sized blow-up Clicking on a lable gives a large blow-up
