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CRYSTAL

Discuss features, updates, and general use of the CRYSTAL module

28 Topics 120 Posts

Subcategories

  • SCF, Convergence, Thresholds, Density Functionals, Spin

    6 Topics
    32 Posts
    matscidannyundefined

    I wanted to understand better how the Fermi level is determined in CRYSTAL. Looking through the manual, I found that there is mention about this in Section 18.7: "The technique adopted to compute EF and the P matrix in the SCF step is described in reference [100]."

    Ref. [100] is the following: V. R. Saunders et al. Electronic structure theory: from molecules to crystals. private communication, 1999.

    The only thing I could find about ref. [100] was this google scholar entry which does not have a link to the article. I was wondering if there is any information about this somewhere else, or if you know where we could have access to the original paper.

  • Input Format, Pseudopotentials

    1 Topics
    9 Posts
    job314undefined

    thank you

  • Internal Coordinates, Constraints, Convergence

    3 Topics
    12 Posts
    Yachao_suundefined

    Thank you very much for the detailed explanation—this really helped clarify things for me! The plot and your explanation made it all very clear.

  • Hessian, Phonons, Quasi-Harmonic Approximation, Anharmonic Force Constants

    2 Topics
    4 Posts
    aerbaundefined

    Hi,

    I think that the best way to proceed in this case would be to restart the calculation one or more times. To do this, you just have to make sure that the scratch folder is not deleted when the calculation stops. Basically, you would run a first job with:

    FREQCALC END

    Then, after the first calculation stops (maybe because you reached a wall clock time limit) you would run a second job restarting from the first as:

    FREQCALC RESTART END

    In order to make this restart work, you need a few files from the previous job to be placed in the scratch folder of the new job: FREQINFO.DAT, fort.13 and fort.9 (to be renamed fort.20 in the new folder).

    If needed, you can repeat this restart process multiple times until completion of the frequency calculation.

    Hope this helps,

  • Harmonic and Anharmonic Vibrational Spectra, Born Tensor, Raman Activities, Phonon Density-of-States

    5 Topics
    10 Posts
    dariagundefined

    Is there a way to restart a Raman calculation that crashed, e.g. for wall time limit on a national supercomputer, at the half of the CPHF cycle (like at the point ELECTRIC FIELD APPLIED ALONG CARTESIAN DIRECTIONS XZ)?

    Thank you

  • Strain, Elastic Tensor, Seismic Waves Velocities

    1 Topics
    3 Posts
    R.Zosiamlianaundefined

    Thank you sir for your kind reply...

  • Stress Tensor

    2 Topics
    13 Posts
    aerbaundefined

    Hi,

    Keeping in mind that geometry optimizations (unconstrained, volume-constrained, pressure-constrained) are all numerical processes with final results that thus may depend on numerical aspects of the implemented algorithms:

    If you are interested in the structure of the true minimum of the PES, the best way to get it is directly from an unconstrained optimization (either from an OPTGEOM calculation or from the PREOPTGEOM within the EOS). By definition, numerically, this is the geometry corresponding to the lowest energy. In both cases, the optimized structure (volume, lattice parameters, atomic positions) is printed in full.

    If, after an EOS calculation, you are interested in getting the structure for a specific volume V (not the minimum), then the strategy you described is exactly what I would do (and I've often done): I make sure to input a structure corresponding to the desired volume (typically by manually adjusting the lattice parameters) and I run a further CVOLOPT calculation.

    Note: During a CVOLOPT calculation the volume of the system is expected to remain almost constant (within a certain numerical error). So small variations may be observed. If instead you experience large variations, there may be a problem.

  • Two-Component Spinors, Non-Collinear Magnetisation, Spin and Particle Currents

    3 Topics
    15 Posts
    Ehsangowdiniundefined

    Thank you so much
    this helped a lot

  • Input Format, Symmetry, Manipulation, Slabs, Nanotubes, Fullerenes, Helices

    2 Topics
    11 Posts
    ywangundefined

    GiacomoAmbrogio

    Dear Ambrogio,

    Thank you so much! the problem has been perfectly solved.

    All the best,

    wang

  • Electric Field, Polarizability, Dielectric Tensor, Hyper-Polarizabilities

    2 Topics
    8 Posts
    masoud37undefined

    Hi,
    Thank you very much for your reply!

    Best regards,
    Masoud

  • Questions that do not fit in other categories

    1 Topics
    3 Posts
    job314undefined

    Thank you very much, that worked (but not restart)