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CRYSTAL

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

22 Topics 91 Posts

Subcategories

  • SCF, Convergence, Thresholds, Density Functionals, Spin

    4 Topics
    20 Posts
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    Hi Alessandro and Giacomo,

    Thank you for the clear and helpful explanations!

    I tried running the calculation with 32 cores, and it indeed helped with memory management. I’ll continue experimenting to optimize performance. Really appreciate your guidance and the references!

  • Input Format, Pseudopotentials

    1 Topics
    9 Posts
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    thank you

  • Internal Coordinates, Constraints, Convergence

    1 Topics
    3 Posts
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    thank you

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

    2 Topics
    4 Posts
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    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

    4 Topics
    9 Posts
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    Thank you very much Jacques and Alessandro.
    Now it works :).
    Best regards
    Xavier

  • Strain, Elastic Tensor, Seismic Waves Velocities

    1 Topics
    3 Posts
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    Thank you sir for your kind reply...

  • Stress Tensor

    2 Topics
    13 Posts
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    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

    2 Topics
    8 Posts
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    No problem. Hope it helps.

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

    2 Topics
    11 Posts
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    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
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    Hi,
    Thank you very much for your reply!

    Best regards,
    Masoud

  • Questions that do not fit in other categories

    1 Topics
    3 Posts
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    Thank you very much, that worked (but not restart)