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PARSEC is a computer code that solves the Kohn-Sham equations by expressing electron wave-functions directly in real space, without the use of explicit basis sets. It uses norm-conserving pseudopotentials (Troullier-Martins and other varieties). It is designed for ab initio quantum-mechanical calculations of the electronic structure of matter, within density-functional theory.

PARSEC is optimized for massively parallel computing environment, but it is also compatible with serial machines. A finite-difference approach is used for the calculation of spatial derivatives. Owing to the sparsity of the Hamiltonian matrix, the Kohn-Sham equations are solved by direct diagonalization, with the use of extremely efficient sparse-matrix eigensolvers. Some of its features are:
  • Choice of boundary conditions: periodic (on all three directions), or confined.
  • Structural relaxation.
  • Simulated annealing.
  • Langevin molecular dynamics.
  • Polarizability calculations (confined-system boundary conditions only).
  • Spin-orbit coupling.
  • Non-collinear magnetism.