# GAMESS-HF-Proxy

**Short Description**

The GAMESS-HF proxy application implements the Hartree-Fock (HF) electronic structure method. The HF method is an integral part of any electronic structure code, and it is also used as a starting point for more advanced electronic correlation methods.

**Institution**

Oak Ridge National Laboratory

**Sponsors**

DOE ECP

**Parent Application/Code**

GAMESS

**Keywords**

Hartree-Fock method, Fock matrix construction

**Programming Languages/Paradigms**

C++, OpenMP

**Website URL**

**Git/SVN Repository URL**

**Release/Version Number**

0.1

**Detailed description**

The GAMESS-HF proxy app implements the Hartree-Fock (HF) electronic structure method. HF is a basic electronic structure theory, which however represents several important aspects of the total molecular energy evaluation -- for instance, calculation of molecular integrals, Fock matrix construction, linear solver for the electron density, etc. The HF is an integral part of any electronic structure code and it is also used as a starting point for more advanced electronic correlation methods. HF is a widely used and may be an example of portable functionality, which may be shared among multiple community codes.
The HF method implementation is straightforward. Nevertheless, the implementation does use common acceleration techniques, such as integral prescreening using Schwarz inequality and direct inversion of the iterative subspace method (DIIS). The HF proxy app relies on the LibInt integral library for evaluation of molecular integrals. Also, basis sets are coming from LibInt.
Parallelization is implemented using OpenMP directives. The rate limiting step of the HF method is the Fock matrix formation. The Fock matrix is constructed using new molecular orbitals in each iteration of the Self-Consistent Field (SCF) optimization. The computational effort is proportional to N4, where N stands for basis set dimension.