• Updated Papers section Papers (2008-10-03)
About APMO

In order to study nuclear quantum effects we have created the Any Particle Molecular Orbital computer package (APMO). The current version of the APMO code is an implementation of the nuclear orbital and molecular orbital approaches (NMO) at the Hartree-Fock level of theory. Currently we have applied the APMO code to a variety of systems to elucidate the isotope effects on electronic wave functions, geometries, dipole moments and electron densities. Although our current version of the code is slower than regular electronic structure packages, our code is robust enough to treat any system containing any combination of quantum particles (i.e. electrons, nuclei, positrons, muons, etc) within a Hartree-Fock  scheme.

We have followed an object-oriented programming philosophy, so that the code can be reutilized and extended. Some classes have been emulated with Fortran and some others constructed with C++. We utilized the latest Fortran language standard  to code the overlap, kinetic energy, nuclear attraction and repulsion integrals routines. These routines were coded  following the recursive formulas proposed by Obara and Saika. We employed the Lapack v3.1.1 library for matrix manipulation.  We used the Fletcher-Reeves conjugate gradient algorithm found in the GSL 1.9 library for geometry optimization.