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Technical Aspects

Seek assistance, discuss troubleshooting tips for any technical problem you encounter and report bugs

12 Topics 69 Posts

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  • Scripts, Objects, Libraries

    3 Topics
    11 Posts
    QMQDCHEMundefined

    Everything works with mpiifx, thank you very much!

  • Pcrystal, MPPcrystal, MPI, OpenMP, GPUs

    6 Topics
    33 Posts
    GiacomoAmbrogioundefined

    Hi Rams,

    The need for relatively high values of FMIXING is not unusual, so what you are observing is expected. That said, you are correct that if FMIXING is set extremely high (close to 100%), there is a risk that the SCF procedure may reach converge before reaching the "true" ground state. This is not unique to your system, it is a general trade-off with strong damping.

    To improve robustness while still guiding the calculation toward the correct solution, you can try:

    Increasing TOLDEE: this tightens the SCF energy convergence criterion and will allow the SCF to continue reaching the minimum even with high FMIXING. Keep in mind, however, that this will typically require many more SCF cycles. Combining mixing with other stabilization strategies, such as level shifting (LEVSHIFT) or electronic smearing (SMEAR) (if applicable to your system), which often reduce the need for such extreme damping.

  • Report bugs with reproduciple example

    3 Topics
    25 Posts
    aerbaundefined

    Hi,

    jquertin said in SCF fails spinlock with POB-DZVP-REV2:

    In the case of SPINLOCK, the manual clearly explain that the NSPIN value is the difference in number of alpha and beta electrons. For SPINLOC2, the text only refers to the spin while the table gives the same definition for SPIN as for NSPIN (in SPINLOCK).

    The argument SPIN of SPINLOC2 still represents a number of electrons, as in SPINLOCK.

    jquertin said in SCF fails spinlock with POB-DZVP-REV2:

    Furthermore, in the calculation, if using SPINLOC2 with 6 or 6.0 as the spin (as defined in the table), crystal defaults to SPINLOCK.

    That's right. SPINLOC2 requires a non integer argument. For integer arguments it reduces to SPINLOCK.

    jquertin said in SCF fails spinlock with POB-DZVP-REV2:

    In short, if I define SPINLOC2 SPIN as 3 (1/2 * 6) or 3.0, crystal defaults to SPINLOCK with NSPIN 3 which is actually half of what I want.

    In both SPINLOCK and SPINLOC2, the argument is meant as a number of electrons. Thus, if you have 6 extra up electrons with respect to down electrons, the input value should be 6, not 3. For integer values, SPINLOC2 is of no use.

    Hope this clarifies things a little,

  • Technical and scientific tips on interfacing CRYSTAL with other software

    0 Topics
    0 Posts
    No new posts.