Dear Mohnish:<br>I have used the 'vc-relax' process optimized the cell parameter, however, the result were seem to deviate from the initial value (experimental value) too much.The aim of the structure optimizes is for calculating the Raman spectra of the structure, I think the bad structure ( not coincide to the experiment) is hard to got the true spectra. So I don't how to deal with the case. According to your experience, what should I do for the next step? <br>
<br>Thank you, dear Mohnish, for your kind help.<br><br><br><br><div class="gmail_quote">2010/9/20 mohnish pandey <span dir="ltr"><<a href="mailto:mohnish.iitk@gmail.com">mohnish.iitk@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Dear Wang,<div> The 'relax' process optimizes the structure within given geometric constraint. It does'nt care for stress. It minimizes force only in the given constraint. If you want to minimize the stress also you have to do 'vc-relax' calculation, It will give you what you want.<br>
<div><br><div class="gmail_quote"><div><div></div><div class="h5">On Mon, Sep 20, 2010 at 11:37 AM, Wang Di <span dir="ltr"><<a href="mailto:didi5158@gmail.com" target="_blank">didi5158@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div><div></div><div class="h5">
Dear all<br><br>I perform the relax calculate to the crystal structure. After 11 step bfgs, the total force and total scf correction had reach to the criterion, however, the total stress was so big P=-3443.87. I have no idea about deal with the case, could anyone give some advices? Thanks in advance.<br>
<br>the input file<br>: &CONTROL<br> calculation = 'scf' ,<br> restart_mode = 'from_scratch' ,<br> wf_collect = .true. ,<br> outdir = '/lustre/AIOFM/gxgu/workLCAF/5/temp/' ,<br>
wfcdir = '/lustre/AIOFM/gxgu/workLCAF/5/wftemp/' ,<br> pseudo_dir = '/home/AIOFM/gxgu/work/NCPP/' ,<br> prefix = 'LCAF' ,<br> etot_conv_thr = 1.0D-7 ,<br>
forc_conv_thr = 1.0D-6 ,<br> nstep = 100 ,<br> tstress = .true. ,<br> tprnfor = .true. ,<br> dipfield = .true. ,<br> /<br> &SYSTEM<br>
ibrav = 4,<br> celldm(1) = 9.42432151,<br> celldm(3) = 1.94804220,<br> nat = 18,<br> ntyp = 4,<br> ecutwfc = 30 ,<br>
ecutrho = 120 ,<br> nosym = .false. ,<br> /<br> &ELECTRONS<br> electron_maxstep = 100,<br> conv_thr = 1.0D-10 ,<br> /<br>ATOMIC_SPECIES<br> Li 6.94100 03-Li.LDA.fhi.UPF <br>
Al 26.98154 13-Al.LDA.fhi.UPF <br> Ca 40.07800 20-Ca.LDA.fhi.UPF <br> F 18.99840 09-F.LDA.fhi.UPF <br>ATOMIC_POSITIONS crystal <br> Li 0.333333333 0.666666667 0.250000000 <br> Li -0.333333333 -0.666666667 -0.250000000 <br>
F 0.389997 0.045970 0.148326 <br> F -0.045970 0.344027 0.148326 <br> F -0.344027 -0.389997 0.148326 <br> F -0.045970 -0.389997 0.351674 <br>
F -0.344027 0.045970 0.351674 <br> F 0.389997 0.344027 0.351674 <br> F -0.389997 -0.045970 -0.148326 <br> F 0.045970 -0.344027 -0.148326 <br>
F 0.344027 0.389997 -0.148326 <br> F 0.045970 0.389997 0.648326 <br> F 0.344027 -0.045970 0.648326 <br> F -0.389997 -0.344027 0.648326 <br>
Al 0.666666667 0.333333333 0.250000000 <br> Al -0.666666667 -0.333333333 -0.250000000 <br> Ca 0.000000000 0.000000000 0.000000000 <br> Ca 0.000000000 0.000000000 0.500000000 <br>
K_POINTS automatic <br> 16 16 16 0 0 0 <br><br>best regart<br><br>Wang Di<br clear="all"><br>-- <br>-----------------------------------------------------------------<br><font color="#888888"><i style="font-family: comic sans ms,sans-serif;">Wang Di</i><i style="font-family: comic sans ms,sans-serif;"><br>
The Crystal Lab,</i><br><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">AnHui Institute of Optics and Fine Mechanics, </span></i><i style="font-family: comic sans ms,sans-serif;"></i><br>
<i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">Chinese Academy of Sciences,</span></i><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US"><br>
No350. , Shushanhu Road, Hefei,
230031, China</span><span style="font-size: 10pt;" lang="EN-US"></span></i><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">,<br>E-mail: didi5158 @gmail.ocm</span></i><i style="font-family: comic sans ms,sans-serif;">
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The Crystal Lab,</i><br><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">AnHui Institute of Optics and Fine Mechanics, </span></i><i style="font-family: comic sans ms,sans-serif;"></i><br>
<i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">Chinese Academy of Sciences,</span></i><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US"><br>
No350. , Shushanhu Road, Hefei,
230031, China</span><span style="font-size: 10pt;" lang="EN-US"></span></i><i style="font-family: comic sans ms,sans-serif;"><span style="font-size: 10pt;" lang="EN-US">,<br>E-mail: didi5158 @gmail.ocm</span></i><i style="font-family: comic sans ms,sans-serif;">
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