PARSEC is made available to the community free of charge, under the GNU General Public License. Please be aware that this code comes as is. We make no warranty with respect to any bugs and we cannot respond to help requests. See our user’s guide for help. Legal issues are covered by the General Public License . Use of the L-BFGS package, part of PARSEC, is also subject to conditions of use.
Version of the code (PARSEC 1.4) can be downloaded. A user’s guide is available.
If you publish work using our code, please cite some of the following articles:
J. R. Chelikowsky, N. Troullier, and Y. Saad, Finite-difference pseudo potential method: Electronic structure calculations without a basis, Phys. Rev. Lett. 72, 1240 (1994).
J. R. Chelikowsky, The pseudopotential-density functional method applied to nanostructures, J. of Phys. D 33, R33 (2000).
L. Kronik, A. Makmal, M.L. Tiago, M.M.G. Alemany, M. Jain, X. Huang, Y. Saad, and J.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).
Y. Saad, J.R. Chelikowsky and S.M. Shontz, Numerical methods for electronic structure calculations of materials, SIAM Rev. 52, 3 (2010).
The first version of NanoGW was developed by Murilo Tiago and James R. Chelikowsky between 2004 and 2009. Later it is developed and maintained by Linda Hung and Weiwei Gao. Weiwei Gao implemented a symmetry-adapted interpolative separable density fitting method to drastically speed up the evaluation of kernel matrix elements in the calculations performed with NanoGW.
NanoGW was originally named as RGWBS, which is more difficult to remember (so we changed the name to “NanoGW”). Since the main advantage of this package is for confined, nanoscale systems, so we call it NanoGW.
What can NanoGW do:
This package can perform the following calculations:
- Linear-response time-dependent density functional theory (by solving Casida equation)
- Full-frequency GW calculation with or without LDA vertex function (does not support spin-orbit coupling)
- Construct and solve Bethe-salpeter equation
This package has been tested thoroughly and optimized for molecules and nanoclusters. It runs particularly efficient for small-size (less than 30 atoms) molecules or clusters. This package can also deal with crystalline systems. However, its functionality for dealing crystals has not been thoroughly tested yet.
We have tested it one a few Linux/Unix machines, including NERSC cori, TACC stampede2, Workstation of Oden institute at UT Austin and personal computers that run Ubuntu or Mac OS. Now it can handles molecules (12 atoms or 50 electrons) with a few minutes and reasonable accuracy on personal computers with a 2-core/4-thread intel processor.
What does NanoGW need as input:
This package requires wave functions and Kohn-Sham energies calculated with PARSEC as input. It also support plane-wave based DFT package PARATEC. NanoGW will convert the plane-wave based wave functions to real-space based wave functions. However, its compatibility with PARATEC has not been thoroughly tested yet.
How to cite this software:
If you find NanoGW is useful and use it for your publication, please cite the following paper:
Tiago, Murilo L. and Chelikowsky, James R, “Optical excitations in organic molecules, clusters, and defects studied by first-principles Green’s function methods,” Phys. Rev. B 73, 205334 (2006).
If you use interpolative separable density fitting (ISDF) to speed up your calculation, please also cite the following paper:
Gao, Weiwei and Chelikowsky, James R., “Accelerating Time-Dependent Density Functional Theory and GW Calculations for Molecules and Nanoclusters with Symmetry Adapted Interpolative Separable Density Fitting,” J. Chem. Theory and Comp. 16, 2216 (2020).