KSDT

Pade fit to the exchange-correlation energy of the 3D homogeneous electron gas.

Use:

Compiling:

Since xc_ksdt_mod.f90 is a Fortran 90 module, compilation is straight-forward:

gfortran xc_ksdt_mod.f90 YOURCODE.f90 -o YOURCODE

To compile the example ksdt.f90:

gfortran xc_ksdt_mod.f90 ksdt.f90 -o ksdt

Functions:

DOUBLE PRECISION FUNCTION exc_ksdt(rs,th,xi)

INPUTS:

• rs = Wigner-Seitz radius, scaled by the Bohr radius
• th = Ratio of temperature to Fermi temperature
• xi = Spin-polarization (1 = polarized, 0 = unpolarized)

RETURNS:

• exc_ksdt = Exchange-correlation energy (Rydbergs)

---

DOUBLE PRECISION FUNCTION dexc_ksdt(rs,th,xi)

INPUT:

• rs = Wigner-Seitz radius, scaled by the Bohr radius
• th = Ratio of temperature to Fermi temperature
• xi = Spin-polarization (1 = polarized, 0 = unpolarized)

RETURNS:

• dexc_ksdt = rs derivative of exc_ksdt (Rydbergs/rs)

---

EXAMPLE USAGE:

PROGRAM main

  USE xc_ksdt_mod
  IMPLICIT NONE
  DOUBLE PRECISION, PARAMETER :: rs = 4.0, th = 1.0, xi = 1
  DOUBLE PRECISION :: exc, dexc

  exc = exc_ksdt(rs,t,xi,exc0)
  dexc = dexc_ksdt(rs,t,xi,exc0,dexc0)
  write(*,*) exc, dexc

END PROGRAM main

Citation

If you use this module in your calculations, please cite both the fit and original Monte Carlo simulation:

V. V. Karasiev, T. Sjostrom, J. Dufty, and S. B. Trickey Local Spi-density Approximation Exchange-correlation Free-energy Functional
ArXiv eprints 1311.4903 (physics.chem-ph)
Submitted to Phys. Rev. B. Rapid Communications (2013)

E. W. Brown, B. K. Clark, J. L. DuBois, and D. M. Ceperley
Path Integral Monte Carlo simulation of the warm-dense homogeneous electron gas
Phys. Rev. Lett. 110, 146405 (2013)

Bibtex:

@ARTICLE{2013arXiv1311.4903K,
   author = {{Karasiev}, V.~V. and {Sjostrom}, T. and {Dufty}, J. and {Trickey}, S.~B.
        },
    title = "{Local Spi-density Approximation Exchange-correlation Free-energy Functional}",
  journal = {ArXiv e-prints},
archivePrefix = "arXiv",
   eprint = {1311.4903},
 primaryClass = "physics.chem-ph",
 keywords = {Physics - Chemical Physics, Condensed Matter - Other Condensed Matter},
     year = 2013,
    month = nov,
   adsurl = {http://adsabs.harvard.edu/abs/2013arXiv1311.4903K},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

@article{PhysRevLett.110.146405,
  title = {Path-Integral Monte~Carlo Simulation of the Warm Dense Homogeneous Electron Gas},
  author = {Brown, Ethan W. and Clark, Bryan K. and DuBois, Jonathan L. and Ceperley, David M.},
  journal = {Phys. Rev. Lett.},
  volume = {110},
  issue = {14},
  pages = {146405},
  numpages = {5},
  year = {2013},
  month = {Apr},
  doi = {10.1103/PhysRevLett.110.146405},
  url = {http://link.aps.org/doi/10.1103/PhysRevLett.110.146405},
  eprint = {1211.6130},
  publisher = {American Physical Society}
}