PARSEC: Pseudopotential algorithm for real-space electronic structure calculations

Current release

This version is PARSEC 1.4. It is the core engine of PARSEC that solves the Kohn–Sham equations.

About PARSEC

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, such as 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 environments but 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 using extremely efficient sparse-matrix eigensolvers.

Some of its features are:

• Choice of boundary conditions: periodic (in 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

How to compile

One can compile PARSEC under the folder src by:

make MACH=ubuntu_intel -j8

where ubuntu_intel is the name of the machine-dependent configuration file in src/config. You may need to adjust some parameters to suit your programming environment.

You can start with some examples (e.g., examples/benchmarks/0d_Si28H36 for 0D systems, examples/tests/bcc for 3D systems, etc.). For instance, navigate to examples/benchmarks/0d_Si28H36 and run the simulation using

mpirun -np 8 ../../../src/parsec-ubuntu_intel-ifx-2024.2.0.mpi

Terms of usage

If you publish work using our code, please cite some of the following papers:

1. James R. Chelikowsky, Norm Troullier, and Yousef Saad, Finite-difference-pseudopotential method: electronic structure calculations without a basis, Physical Review Letters 72, 1240 (1994).
2. James R. Chelikowsky, The pseudopotential-density functional method applied to nanostructures, Journal of Physics D: Applied Physics 33, R33 (2000).
3. Leeor Kronik, Adi Makmal, Murilo L. Tiago, Manuel M. G. Alemany, Manish Jain, Xiangyang Huang, Yousef Saad, and James R. Chelikowsky, PARSEC – the pseudopotential algorithm for real-space electronic structure calculations: recent advances and novel applications to nano-structures, Physica Status Solidi (b) 243, 1063 (2006).
4. Yousef Saad, James R. Chelikowsky, and Suzanne M. Shontz, Numerical methods for electronic structure calculations of materials, SIAM Review 52, 3 (2010).