[Pw_forum] Fw: SCF convergence in magnetic system during vc-relax
talpha beta
talphabeta at yahoo.com
Sun Mar 1 15:32:34 CET 2015
Pang, when you advise to change mixing steps, are you suggesting to change mixing_ndim or mixing_fixed_ns ? I'm not sure the effect of either one, can you please explain?Turning off spin polarization might get to a different ionic ground state -- I'm starting from a converged ionic ground state and then changing the doping by swapping out one atom per unit cell, so I'm already fairly close to a ground state, and I'm just trying to get the last increment of convergence.
Thanks MVKondrin. etot_conv_thr, as I understand it, controls the delta E convergence threshold between ionic steps of a geometry relaxation (i.e. after electron SCF convergence in a given geometry). I'm seeing non-convergence in SCF steps, and I believe conv_thr (&electrons namelist) controls the SCF convergence. A fair question would be, "should I increase conv_thr?" -- to which I'm taking a conservative route and hoping to get good SCF convergence in each ion step.
On Sunday, February 22, 2015 6:53 AM, MKondrin <mkondrin at hppi.troitsk.ru> wrote:
talpha beta wrote:
> I'm having lots of trouble getting SCF convergence during a vc-relax
> calculation. The first ~30 geometry relaxation steps will converge,
> and then at some point, it doesn't reach convergence, and restarting
> from there doesn't obtain convergence with a variety of input
> parameters. I allow up to 400 steps for convergence; the calculation
> gets close to energy convergence in the first ~40 steps and then
> oscillates like this:
>
>
>
> total energy = -3730.97262054 Ry
> total energy = -3730.97260717 Ry
> total energy = -3730.97261229 Ry
> total energy = -3730.97261830 Ry
> total energy = -3730.97258457 Ry
> total energy = -3730.97261372 Ry
> total energy = -3730.97268144 Ry
> total energy = -3730.97262740 Ry
> total energy = -3730.97259749 Ry
> total energy = -3730.97264306 Ry
> total energy = -3730.97263999 Ry
> total energy = -3730.97266124 Ry
> total energy = -3730.97263072 Ry
> total energy = -3730.97261754 Ry
> total energy = -3730.97260856 Ry
> total energy = -3730.97261221 Ry
> total energy = -3730.97282659 Ry
> total energy = -3730.97252377 Ry
> total energy = -3730.97259997 Ry
> total energy = -3730.97261600 Ry
> total energy = -3730.97264186 Ry
> total energy = -3730.97263070 Ry
> total energy = -3730.97260955 Ry
> total energy = -3730.97267593 Ry
> total energy = -3730.97263180 Ry
> total energy = -3730.97259580 Ry
> total energy = -3730.97269934 Ry
> total energy = -3730.97275706 Ry
> total energy = -3730.97245909 Ry
> total energy = -3730.97258422 Ry
> total energy = -3730.97257852 Ry
> total energy = -3730.97255901 Ry
> total energy = -3730.97259179 Ry
> total energy = -3730.97262199 Ry
> total energy = -3730.97259627 Ry
> total energy = -3730.97261363 Ry
> total energy = -3730.97262780 Ry
> total energy = -3730.97273314 Ry
> total energy = -3730.97251796 Ry
> total energy = -3730.97259430 Ry
> total energy = -3730.97258802 Ry
> total energy = -3730.97257319 Ry
> total energy = -3730.97257817 Ry
> total energy = -3730.97254693 Ry
> total energy = -3730.97253977 Ry
> total energy = -3730.97254394 Ry
> total energy = -3730.97254471 Ry
> total energy = -3730.97282186 Ry
> total energy = -3730.97250548 Ry
> total energy = -3730.97248482 Ry
> total energy = -3730.97247040 Ry
> total energy = -3730.97239243 Ry
> total energy = -3730.97226787 Ry
> total energy = -3730.97222104 Ry
> total energy = -3730.97219271 Ry
> total energy = -3730.97222772 Ry
> total energy = -3730.97244430 Ry
> total energy = -3730.97291917 Ry
> total energy = -3730.97279625 Ry
> total energy = -3730.97207455 Ry
> total energy = -3730.97249466 Ry
> total energy = -3730.97247870 Ry
> total energy = -3730.97252112 Ry
> total energy = -3730.97253986 Ry
> total energy = -3730.97254804 Ry
> total energy = -3730.97264250 Ry
> total energy = -3730.97257019 Ry
> total energy = -3730.97258495 Ry
> total energy = -3730.97282802 Ry
> total energy = -3730.97259481 Ry
> total energy = -3730.97254903 Ry
> total energy = -3730.97252576 Ry
> total energy = -3730.97249424 Ry
> total energy = -3730.97237618 Ry
> total energy = -3730.97263210 Ry
> total energy = -3730.97248594 Ry
> total energy = -3730.97240941 Ry
> total energy = -3730.97283533 Ry
> total energy = -3730.97270373 Ry
> total energy = -3730.97250770 Ry
> total energy = -3730.97252933 Ry
> total energy = -3730.97254547 Ry
> total energy = -3730.97250286 Ry
> total energy = -3730.97247847 Ry
> total energy = -3730.97244537 Ry
> total energy = -3730.97244642 Ry
> total energy = -3730.97241718 Ry
> total energy = -3730.97242648 Ry
> total energy = -3730.97296957 Ry
> total energy = -3730.97258207 Ry
> total energy = -3730.97250996 Ry
> total energy = -3730.97271424 Ry
> total energy = -3730.97258977 Ry
> total energy = -3730.97259733 Ry
> total energy = -3730.97264651 Ry
> total energy = -3730.97263695 Ry
> total energy = -3730.97259491 Ry
> total energy = -3730.97261988 Ry
> total energy = -3730.97272206 Ry
> total energy = -3730.97261538 Ry
> total energy = -3730.97256870 Ry
> total energy = -3730.97252499 Ry
> total energy = -3730.97252092 Ry
> total energy = -3730.97252172 Ry
> total energy = -3730.97257641 Ry
> total energy = -3730.97256721 Ry
> total energy = -3730.97257116 Ry
> total energy = -3730.97256679 Ry
> total energy = -3730.97274213 Ry
> total energy = -3730.97253146 Ry
> total energy = -3730.97249600 Ry
> total energy = -3730.97250428 Ry
> total energy = -3730.97254304 Ry
> total energy = -3730.97256978 Ry
> total energy = -3730.97273656 Ry
> total energy = -3730.97248342 Ry
> total energy = -3730.97240302 Ry
> total energy = -3730.97243408 Ry
> total energy = -3730.97241248 Ry
> total energy = -3730.97238562 Ry
> total energy = -3730.97251359 Ry
> total energy = -3730.97247234 Ry
> total energy = -3730.97264369 Ry
> total energy = -3730.97259674 Ry
> total energy = -3730.97266736 Ry
> total energy = -3730.97257325 Ry
> total energy = -3730.97247542 Ry
> total energy = -3730.97252150 Ry
> total energy = -3730.97248097 Ry
> total energy = -3730.97246945 Ry
> total energy = -3730.97253380 Ry
> total energy = -3730.97255385 Ry
> total energy = -3730.97254624 Ry
> total energy = -3730.97277355 Ry
> total energy = -3730.97261952 Ry
> total energy = -3730.97255316 Ry
> total energy = -3730.97253355 Ry
> total energy = -3730.97247700 Ry
> total energy = -3730.97253033 Ry
> total energy = -3730.97247318 Ry
> total energy = -3730.97244662 Ry
> total energy = -3730.97246907 Ry
> total energy = -3730.97244103 Ry
> total energy = -3730.97306304 Ry
> total energy = -3730.97245649 Ry
> total energy = -3730.97247788 Ry
> total energy = -3730.97281807 Ry
> total energy = -3730.97269524 Ry
> total energy = -3730.97274703 Ry
> total energy = -3730.97267068 Ry
> total energy = -3730.97251186 Ry
> total energy = -3730.97245086 Ry
> total energy = -3730.97258230 Ry
>
> I input a starting_magentization value close to the converged values
> from previous runs
> I increase the number of bands (nbnd) to well above #electrons/2
> diagonalization = 'cg' or 'david'
> electron_maxstep = 400
> mixing_mode = 'plain' or 'local-TF'
> mixing_beta = as low as 0.05
>
> what are the other tricks/tips to obtain convergence?
>
>
> ------------------------------------------------------------------------
>
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Wouldn't you just increase etot_conv_thr (in &control namelist) to some
larger value? The total energy is high enough so the oscillation at the
level of 1e-8 of the absolute value may be due to the calculation errors.
M. V. Kondrin
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