<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=gb2312" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 8.00.6001.19019">
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT size=2 face=Arial>Hi,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I'm trying to run a vc-md simulation of a supercell
with 80 atoms at 300 K and 20 GPa,</FONT></DIV>
<DIV><FONT size=2 face=Arial>but the SCF convergence is always failed
to reach after 20 or so ion steps no matter </FONT></DIV>
<DIV><FONT size=2 face=Arial>how I change mixing_beta from 0.5 to 0.05. One
thing I noticed is that the temperature</FONT></DIV>
<DIV><FONT size=2 face=Arial>controling may be not in effect as the temperature
remains as high as 6 digits. I used </FONT></DIV>
<DIV><FONT size=2 face=Arial>the 'rescaling' , the only setting available for
vc-md, for ion_temperature, the default </FONT></DIV>
<DIV><FONT size=2 face=Arial>100.0 for tolp. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Below is part of my input file, any comments are
welcome. I would also like to know</FONT></DIV>
<DIV><FONT size=2 face=Arial>which source file I need to look at for the
rescaling function.</FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The same system is running without any problem
using CP dynamics in VASP and </FONT></DIV>
<DIV><FONT size=2 face=Arial>CASTEP. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial> &control<BR>
calculation = 'vc-md',<BR> restart_mode =
'from_scratch',<BR> prefix = 'mgsio3',<BR>
tstress = .true.,<BR> tprnfor = .true.,<BR>
pseudo_dir = '/home/hqzhou/qe_pseudo/',<BR> outdir =
'/gpfsTMP/hqzhou/tmp/'<BR> wf_collect =
.true.<BR> nstep = 100<BR> dt =
20.0<BR> /<BR> &system<BR> !ibrav =
0<BR> !celldm(1) = 0.0<BR> ibrav =
14<BR> celldm(1) = 18.0484, celldm(2) = 1.0322, celldm(3) =
0.7221<BR> celldm(4) = 0.0, celldm(5) = 0.0, celldm(6) =
0.0<BR> nat = 80, ntyp = 3,<BR> ecutwfc =
40.0, ecutrho = 400.0<BR> nspin = 1<BR>
nosym = .true.<BR> occupations =
'fixed'<BR> /<BR> &electrons<BR>
electron_maxstep = 200<BR> diagonalization =
david<BR> mixing_mode = 'plain'<BR>
mixing_beta = 0.1<BR> conv_thr =
1.0d-8<BR> /<BR> &ions<BR> ion_dynamics =
'beeman'<BR> pot_extrapolation =
'second_order'<BR> wfc_extrapolation =
'second_order'<BR> upscale = 100.0<BR>
ion_temperature = 'rescaling'<BR> tempw =
300.0<BR> refold_pos =
.true.<BR> /<BR> &cell<BR> cell_dynamics =
'pr'<BR> press = 200.0<BR> !wmass =
0.05<BR> cell_factor = 1.6<BR>
press_conv_thr = 0.2<BR> /<BR>......</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thanks in advance.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>zhou huiqun</FONT></DIV>
<DIV><FONT size=2 face=Arial>@earth sciences, nanjing university,
china</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV></BODY></HTML>