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CRYSTAL

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

58 Topics 273 Posts

Subcategories

  • SCF, Convergence, Thresholds, Density Functionals, Spin

    11 Topics
    47 Posts
    CaesarSaladundefined

    Hi Giacomo,

    That's a very useful answer, thank you!

    Chris

  • Input Format, Pseudopotentials

    2 Topics
    15 Posts
    job314undefined

    Alessandro, the setback is temporary. What I really appreciate is that you gave CRYSTAL more life via user support than it ever had. I am very grateful for it

  • Internal Coordinates, Constraints, Convergence

    9 Topics
    39 Posts
    fbodoundefined

    Dear esmuigors
    esmuigors said in Unexpectedly cannot get the geometry after optimization: KEYWORD EXTPRT NOT ALLOWED:

    Should I only take the atoms labelled by "T" if the lattice is tetragonal, and which ones are to be taken in case of an orthorombic one? Or does "T"'and "F" stand just for "TRUE"'and "FALSE"?

    You are correct T and F stand for 'TRUE' and 'FALSE'.

    esmuigors said in Unexpectedly cannot get the geometry after optimization: KEYWORD EXTPRT NOT ALLOWED:

    I am actually talking about the standard runPcry23 script. Perhaps it should not be like that? Or should I modify this script?

    That script already contain the few line of codes I suggested you, if not feel free to modify it and add those lines.

    esmuigors said in Unexpectedly cannot get the geometry after optimization: KEYWORD EXTPRT NOT ALLOWED:

    Actually, I have now tried using only the "T"-labeled atoms and got this error:

    ERROR **** geometry **** FORMAT ERROR IN INPUT DECK

    I checked the input on top of the CS2_B1WC.pob_tzvp_rev2_gamma_onlyT.out file it seems like you are defining six atoms in the asymmetric unit, but only two atomic positions are specified in the input.

    CRYSTAL 0 0 0 64 6.34350113 5.54788046 9.71085545 6. ! Definitions of the number of atoms in the asymmetric unit 6 0.000000000000e+00 0.000000000000e+00 -5.000000000000e-01 16 2.303037287581e-17 3.119080311720e-01 1.207617820468e-01 ATOMSYMM ...

    The number of atoms in the asymmetric unit and the position specified should always match.

    I hope this helps you,

    Best,

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

    5 Topics
    20 Posts
    spiekermannundefined

    Dear Alessandro,
    thank you for this explanation!
    Kind regards,
    Georg

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

    12 Topics
    57 Posts
    PeterRemotoundefined

    aerba I've noticed for my systems, these SCF convergence issues appear when I try to compute for intensities in a restart job. Then when removing intensities, they converge fine and progress forward.

    Is it possible to finish the frequency calculations first and then compute for the Raman intensities afterwards? Would that be a work around? Maybe with RAMANREA - because I have the TENS_RAMAN.DAT, but it just gets stuck at some point during HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
    FORCE CONSTANT MATRIX - NUMERICAL ESTIMATE
    HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
    and doesn't progress with restarts

  • Strain, Elastic Tensor, Seismic Waves Velocities

    2 Topics
    5 Posts
    aerbaundefined

    Hi,

    Direct piezoelectric constants of a 3D lattice in CRYSTAL are defined and computed as:
    $$
    e_{ci}^{3D} = \left( \frac{\partial P_c}{\partial \eta_i}\right) = \frac{1}{V}\left( \frac{\partial^2 E}{\partial E_c\partial \eta_i}\right)
    $$
    that is as first derivatives of Cartesian components of the polarization (c=x,y,z) with respect to strain components, or, equivalently as second derivatives of the energy density (V is the volume of the 3D lattice cell) with respect to Cartesian components of an electric field \(E_c\) and strain components, where the strain \( \eta \) is dimensionless and thus the direct piezoelectric constants have units of \( \textup{charge/length}^2 \).

    For 1D and 2D periodic lattices, as the volume (V) is not uniquely defined (or not defined at all in some cases), one may divide by the length \(l \) and area \( A\) of the lattice cell instead:
    $$
    e_{ci}^{1D} = \frac{1}{l}\left( \frac{\partial^2 E}{\partial E_c\partial \eta_i}\right) \quad \textup{and} \quad e_{ci}^{2D} = \frac{1}{A}\left( \frac{\partial^2 E}{\partial E_c\partial \eta_i}\right)
    $$
    that would thus be expressed in units of \( \textup{charge} \) or \( \textup{charge/length} \) for 1D and 2D lattices, respectively.

    However, in CRYSTAL for 1D and 2D lattices we do not divide by \(l \) or \( A\) , and just define and compute the piezoelectric constants as:
    $$
    e_{ci}^\textup{1D and 2D} = \left( \frac{\partial^2 E}{\partial E_c\partial \eta_i}\right)
    $$
    with units of \( \textup{charge}\cdot\textup{length} \).

    Yes, these constants are physically meaningful for 1D and 2D systems. For a 2D monolayer system, for instance, depending on what you need to compare with, you can do one of two things:

    keep them as they are printed in the CRYSTAL output (units of \( \textup{charge}\cdot\textup{length} \))

    divide the values you get in the CRYSTAL output by the area of the 2D cell (and thus express them in units of \( \textup{charge/length} \))

    I would not divide by a volume because I would not know the physical meaning of the volume of a 2D monolayer system.

    Hope this helps,

  • Stress Tensor

    2 Topics
    24 Posts
    aerbaundefined

    For the purpose of finding the minimum energy structure to then do Raman calculations, it is.

    EOS gives you much more than that of course: the p(V) or, equivalently, V(p) relation (i.e. structure as a function of pressure), the bulk modulus K(p), and allows to compute the enthalpy H(p).

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

    5 Topics
    25 Posts
    CaesarSaladundefined

    Thanks Giacomo, much appreciated,

    Chris

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

    5 Topics
    20 Posts
    job314undefined

    Hi Giu, it worked!

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

    4 Topics
    18 Posts
    esmuigorsundefined

    To clarify better, does the symmetrization correspond to the frequency symmetry (which determines the equal components, e.g., xxyy = xyxy = xyyx, etc. for the static case?
    Or is this about the geometrical symmetry (and possible reorientation of the molecule to have the dipole moment along an axis)?

  • Questions that do not fit in other categories

    1 Topics
    3 Posts
    job314undefined

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