TY - JOUR
T1 - Numerical Methods for Solving the Hartree-Fock Equations of Diatomic Molecules II
AU - John C. Morrison, Kyle Steffen, Blake Pantoja, Asha Nagaiya, Jacek Kobus & Thomas Ericsson
JO - Communications in Computational Physics
VL - 3
SP - 632
EP - 647
PY - 2018
DA - 2018/04
SN - 19
DO - http://doi.org/10.4208/cicp.101114.170615a
UR - https://global-sci.org/intro/article_detail/cicp/11103.html
KW - 
AB - <p style="text-align: justify;">In order to solve the partial differential equations that arise in the Hartree-Fock
theory for diatomic molecules and in molecular theories that include electron correlation,
one needs efficient methods for solving partial differential equations. In this
article, we present numerical results for a two-variable model problem of the kind that
arises when one solves the Hartree-Fock equations for a diatomic molecule. We compare
results obtained using the spline collocation and domain decomposition methods
with third-order Hermite splines to results obtained using the more-established finite
difference approximation and the successive over-relaxation method. The theory of
domain decomposition presented earlier is extended to treat regions that are divided
into an arbitrary number of subregions by families of lines parallel to the two coordinate
axes. While the domain decomposition method and the finite difference approach
both yield results at the micro-Hartree level, the finite difference approach with a 9-point difference formula produces the same level of accuracy with fewer points. The
domain decomposition method has the strength that it can be applied to problems with
a large number of grid points. The time required to solve a partial differential equation
for a fine grid with a large number of points goes down as the number of partitions
increases. The reason for this is that the length of time necessary for solving a set of
linear equations in each subregion is very much dependent upon the number of equations.
Even though a finer partition of the region has more subregions, the time for
solving the set of linear equations in each subregion is very much smaller. This feature
of the theory may well prove to be a decisive factor for solving the two-electron pair
equation, which – for a diatomic molecule – involves solving partial differential equations
with five independent variables. The domain decomposition theory also makes
it possible to study complex molecules by dividing them into smaller fragments that&nbsp;are calculated independently. Since the domain decomposition approach makes it possible
to decompose the variable space into separate regions in which the equations are
solved independently, this approach is well-suited to parallel computing.</p>