PARSEC is a package designed to perform electronic structure calculations of solids and molecules using density functional theory

Density functional theory

Density functional theory is a quantum mechanical modelling method used in physics and chemistry to investigate the electronic structure of many-body systems, in particular atoms, molecules, and the condensed phases. With this theory, the properties of a many-electron system can be determined by...

 (DFT). The acronym stands for Pseudopotential Algorithm for Real-Space Electronic Calculations.. It solves the Kohn-Sham equations

Kohn-Sham equations

In quantum chemistry, specifically density functional theory, the Kohn–Sham equation is the Schrödinger equation of a fictitious system of non-interacting particles that generate the same density as any given system of interacting particles...

 in real space, without the use of explicit basis sets

Basis set (chemistry)

A basis set in chemistry is a set of functions used to create the molecular orbitals, which are expanded as a linear combination of such functions with the weights or coefficients to be determined. Usually these functions are atomic orbitals, in that they are centered on atoms. Otherwise, the...

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One of the strengths of this code is that it handles non-periodic boundary conditions in a natural way, without the use of super-cells, but can equally well handle periodic and partially periodic boundary conditions.,,. Another key strength is that it is readily amenable to efficient massive parallelization, making it highly effective for very large systems.

Its development started in early 1990s with James Chelikowsky (now at the University of Texas), Yousef Saad

Yousef Saad

Yousef Saad is an I.T. Distinguished Professor of Computer Science in the Department of Computer Science and Engineering at the University of Minnesota. He holds the William Norris Chair for Large-Scale Computing since January 2006...

 and collaborators at the University of Minnesota

University of Minnesota

The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...

. The code is freely available under the GNU GPLv2. Currently, its public version is 1.3.6. Some of the physical/chemical properties calculated by this code are: Kohn-Sham band structure, atomic forces (including molecular dynamics capabilities), static susceptibility

Electric susceptibility

In electromagnetism, the electric susceptibility \chi_e is a dimensionless proportionality constant that indicates the degree of polarization of a dielectric material in response to an applied electric field...

, magnetic dipole moment, and many additional molecular and solid state properties.