<div dir="ltr"><div>Interlayer distances in layered materials are more often than not badly described by plain GGA. Keep the layer-layer distance fixed if you really want to use vc-relax (cell_dofree='2Dxy' should do that; no warranty)<br><br></div>Paolo<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 16, 2016 at 9:03 PM, David Foster <span dir="ltr"><<a href="mailto:davidfoster751@yahoo.com" target="_blank">davidfoster751@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear Users and Developers,<br>
I have constructed supercell of N-doped Graphene and then somewhat enlarged its lattice parameres a and b (and of course a is equal to b). However, it finished with following issue:<br>
<br>
======================<br>
Error in routine scale_h (1):<br>
Not enough space allocated for radial FFT: try restarting with a larger cell_factor.<br>
==========================<br>
<br>
This is my input:<br>
<br>
<br>
==========================================================<br>
&CONTROL<br>
title = 'graph55'<br>
calculation = 'vc-relax'<br>
restart_mode = 'from_scratch'<br>
outdir = './graph55',<br>
pseudo_dir = './'<br>
prefix = 'graph55'<br>
disk_io = 'default'<br>
verbosity = 'default'<br>
etot_conv_thr=1.0D-7<br>
forc_conv_thr=1.0D-4<br>
nstep=1000<br>
/<br>
&SYSTEM<br>
ibrav = 4<br>
nat = 50<br>
celldm(1)=23.489294<br>
celldm(3)=1.206758<br>
ntyp = 2<br>
ecutwfc = 50<br>
ecutrho = 400<br>
starting_magnetization(1)=0.0<br>
starting_magnetization(2)=0.5<br>
nspin=2<br>
occupations='smearing'<br>
degauss=0.001<br>
smearing='mv'<br>
nbnd=480<br>
<br>
/<br>
&ELECTRONS<br>
electron_maxstep = 1000<br>
conv_thr = 1.0D-8<br>
mixing_mode = 'plain'<br>
mixing_beta = 0.6<br>
mixing_ndim = 15<br>
diagonalization = 'david'<br>
/<br>
&IONS<br>
ion_dynamics = 'bfgs'<br>
/<br>
&CELL<br>
cell_dynamics = 'bfgs'<br>
/<br>
ATOMIC_SPECIES<br>
C 12.0107 C.revpbe-n-kjpaw_psl.1.0.0.UPF<br>
N 14.0067 N.revpbe-n-kjpaw_psl.1.0.0.UPF<br>
ATOMIC_POSITIONS crystal<br>
C -0.0035332843482924 0.1851606795737290 0.0007869079000000<br>
C 0.0634271391536306 0.1185672123378320 0.0007985082000000<br>
C 0.1972118104100160 0.1853479022359610 0.0008411762000000<br>
C 0.2640546796835970 0.1183863082006620 0.0009013451000000<br>
C 0.3969086810996360 0.1847817800592880 0.0009532216000000<br>
C 0.5956703644545790 0.1847899234385230 0.0009535323000000<br>
C 0.6620952820613830 0.1183858687084460 0.0008990575000000<br>
C 0.7959137330003590 0.1853435760570340 0.0008381939000000<br>
C 0.8629092298955131 0.1185585471602930 0.0007960819000000<br>
C -0.0035150546870443 0.3851557202317041 0.0007940836000000<br>
C 0.0631838589318034 0.3186049498829150 0.0007792434000000<br>
C 0.1964457156160120 0.3851562851338740 0.0007933639000000<br>
C 0.2632838872396650 0.3184362406096610 0.0008320941000000<br>
C 0.3962746887700520 0.3844348851829029 0.0008478821000000<br>
C 0.4633829529931270 0.3177351000329150 0.0009047888000000<br>
C 0.5966074788692490 0.3854315630482320 0.0008457238000000<br>
C 0.6621190897524240 0.3177365375096750 0.0009084184000000<br>
C 0.7959398316409772 0.3844368174251561 0.0008509560000000<br>
C 0.8629199294456980 0.3184362167353211 0.0008339366000000<br>
C -0.0035338673838872 0.5851396932290081 0.0008066546000000<br>
C 0.0631828018860480 0.5185244995082190 0.0007939395000000<br>
C 0.1964417765107390 0.5851050828686231 0.0008011519000000<br>
C 0.2631050290407810 0.5185229929166390 0.0007907967000000<br>
C 0.3964498615623250 0.5851408711536121 0.0008013268000000<br>
C 0.4631600273382970 0.5183053159798940 0.0008129827000000<br>
C 0.5962440563130300 0.5850417316123839 0.0007996048000000<br>
C 0.6630008615229410 0.5182306760627760 0.0008043849000000<br>
C 0.7965775260836450 0.5850387078390509 0.0008039151000000<br>
C 0.8629155401533460 0.5183093186011401 0.0008193526000000<br>
C -0.0033916823133423 0.7850662361778210 0.0007997306000000<br>
C 0.0634101234250425 0.7187980286682670 0.0008217964000000<br>
C 0.1971891482432570 0.7856552562612531 0.0008570577000000<br>
C 0.2632663498936130 0.7187701364726640 0.0008505618000000<br>
C 0.3962428547644810 0.7856593672924379 0.0008523345000000<br>
C 0.4631548736327530 0.7187974024545640 0.0008142026000000<br>
C 0.5962365218114650 0.7850664959157701 0.0007908983000000<br>
C 0.6630323786577090 0.7185060088037540 0.0007742824000000<br>
C 0.7964705953600870 0.7851503463114868 0.0007759114000000<br>
C 0.8632460667289600 0.7185087677298430 0.0007795964000000<br>
C -0.0034053781659958 0.9853764016728360 0.0007854744000000<br>
C 0.0635533974119052 0.9187469611954919 0.0008003277000000<br>
C 0.1962427491566600 0.9850440103004491 0.0008482846000000<br>
C 0.2640035494748090 0.9195524304057730 0.0009266913000000<br>
C 0.3968289999039731 0.9858822472737551 0.0009841481000000<br>
C 0.4633106954544801 0.9195552131133050 0.0009214067000000<br>
C 0.5965808827582050 0.9850424408181000 0.0008394477000000<br>
C 0.6629579286767470 0.9187453484234860 0.0007918820000000<br>
C 0.7965538253125150 0.9853722213410399 0.0007802641000000<br>
C 0.8632342863818040 0.9186931763034320 0.0007636222000000<br>
N 0.4631246241068560 0.1185000696135500 0.0009700199000000<br>
K_POINTS automatic<br>
4 4 1 0 0 0<br>
<br>
=====================================================<br>
<br>
It seems it is better not to use vc-relax, and instead use relax+changing volume by hand :-)<br>
Anybody can help to solve this problem?<br>
<br>
Regards<br>
<br>
David Foster<br>
<br>
Ph.D. Student of Chemistry<br>
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</blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br><br></div></div></div></div></div>
</div>