CLUPAN v0.7 documentation

1. Overview of CLUPAN

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1. Overview of CLUPAN

1.1. Cluster expansion method and thermodynamic calculations using CLUPAN

  • Evaluation of effective cluster interactions (ECI) using the cluster expansion (CE) method.
  • Calculation of energies for structures using ECI.
  • Monte Carlo simulations using ECI.
  • Free energy calculation based on thermodynamics integration combined with Monte Carlo simulations.
  • Iterative procedure to perform the CE.

See [CE1] to find the details of the procedure.

[CE1]A Seko, Y Koyama and I Tanaka, Phys. Rev. B 80, 165122 (2009).

1.2. Framework of CLUPAN

CLUPAN is composed of the following programs.

main programs

  • Searching for symmetrically-independent structures
    • mkposcar
  • Searching for symmetrically-independent clusters
    • cluster
  • Calculating correlation functions of a structure
    • correlation
  • Estimating ECIs using the least-squares method
    • lsf, wlsf
  • Optimizing cluster set using the genetic algorithm and the simulated annealing
    • gasa, wgasa
  • Searching for DFT structures that improves the estimated ECIs
    • search_poscar
  • Searching for ground state structures using the ECIs
    • gss
  • Performing Monte Carlo simulations using the ECIs
    • cmc, gcmc
  • estimating the grand potential using the thermodynamic integration
    • ti

sub programs

  • Evaluating the variance of correlation functions and the correlation between correlation functions of two clusters
    • statistic
  • Calculating the mean variance of the predicted energy
    • variance_energy
  • Generating VARIANCE and MEAN files required in search_poscar_variance
    • variance_stpop
  • Estimating the grand potential using the low temperature expansion
    • lte

1.3. Examples of calculations by using CLUPAN

Predicting cation disordering in spinel oxides [CE2]

Exploring stable structures in tin oxides [CE3]

[CE2]A Seko, K Yuge, F Oba, A Kuwabara and I Tanaka, Phys. Rev. B 73, 184117 (2006).
[CE3]A Seko, A Togo, F Oba and I Tanaka, Phys. Rev. Lett. 100, 045702 (2008).

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