mirror of https://gitlab.com/QEF/q-e.git
58 lines
2.1 KiB
Plaintext
58 lines
2.1 KiB
Plaintext
This example shows how to use the vdw-DF functional in pw.x. It
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calculates the non-local correlation contribution to the energy and
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potential according to
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M. Dion, H. Rydberg, E. Schroeder, D.C. Langreth, and
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B.I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004).
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henceforth referred to as DION. Further information about the
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functional and its corresponding potential can be found in:
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T. Thonhauser, V.R. Cooper, S. Li, A. Puzder, P. Hyldgaard,
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and D.C. Langreth, Phys. Rev. B 76, 125112 (2007).
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The proper spin extension of vdW-DF, i.e. svdW-DF, is derived in
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T. Thonhauser, S. Zuluaga, C.A. Arter, K. Berland, E. Schroder,
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and P. Hyldgaard, Phys. Rev. Lett. 115, 136402 (2015).
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henceforth referred to as THONHAUSER.
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Two review articles show many of the vdW-DF applications:
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D.C. Langreth et al., J. Phys.: Condens. Matter 21, 084203 (2009).
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K. Berland et al., Rep. Prog. Phys. 78, 066501 (2015).
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The method implemented is based on the method of G. Roman-Perez and
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J.M. Soler described in:
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G. Roman-Perez and J.M. Soler, Phys. Rev. Lett. 103, 096102 (2009).
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henceforth referred to as SOLER.
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The example will first check if all the necessary files are present, and
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then run the simulations. After the check, the example will proceed with
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two simulations, in particular
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1) A variable cell relaxation of a simple 1x1 graphite. The parameters
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used (such as k-point mesh and energy cutoffs) are not converged, use them
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only for test runs, increase them accordingly for production runs.
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Here the stress will be used to converge the cell at 0 pressure.
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2) A self-consistent energy calculation of a water dimer in the
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equilibrium configuration. Check the energies and forces against
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those in the reference file.
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bonus) If you have the Ar.pz-rrkj.UPF in the PP_dir, you can activate the
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last example by removing the comments from the execution lines (277-280).
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In this example it is shown how to run a BFGS relaxation of the forces
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for the Argon dimer. Check that the energies and forces agree with those
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in the reference file, and that the final positions are correct.
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