[CPMD-list] Stress cal.

[Dai Ling]

Dear CPMD experts:
 
I want to study the stress of a cluster of Ta atoms. Running a geometry optimization to relax the structure, I found the stress tensor increases after the geometry optimization. Therefore, I have some questions below:
 
1. How is the stress tensor obtained from CPMD?
2. According to previous mails, it seems Pulay correction is requied for an accurate stress tensor. Anybody can help to tell me the procedure for a stress correction?
 
Thanks in advance!
 
Scott
 
Attach is my input file
 
&CPMD
OPTIMIZE GEOMTRY
.....
STRESS TENSOR
.....
&END
&SYSTEM
ANGSTROM
CELL ABSOLUTE DEGREE
8.0200    8.0200   25.000   90.0000   90.0000   90.0000
SYMMETRY
8
CUTOFF
80
&END
 
&DFT
NEWCODE
FUNCTIONAL BLYP 
&END
 
&ATOMS
*Ta_MT_BLYP.psp KLEINMAN-BYLANDER                
LMAX=D LOC=D                                     
24                                               
1.458964212 1.642781404 12.85528974
1.302210889 4.70818129 14.02294841
4.121288277 1.136884698 11.26407241
3.737582599 4.346721388 11.87598699
5.869150858 -1.545731206 10.40377418
6.865933118 3.620061218 11.47434596
9.477668314 3.390701323 9.721818565
9.331118544 6.583036724 10.95980435
2.967248939 0.1517192 18.5715481
0.995939304 7.307594207 16.01246407
3.889406009 2.056852945 15.11172355
3.696847068 6.971603819 14.00419011
6.723771222 -0.004106588 13.44204804
6.152232275 4.569026333 14.75305913
8.639152758 2.561859413 16.54645995
8.188196831 5.390025214 18.74376455
4.934712963 1.006965386 21.29881767
3.319805687 4.999628362 16.89237238
5.563662985 2.901173349 18.20624566
5.833026266 7.510751215 16.76322654
7.840485255 0.621593954 19.54509749
5.070970041 5.817719157 19.95986794
10.52031432 3.203152177 19.98871173
10.12308039 6.721329941 21.57080296

&END