<div class="gmail_quote">Vikas, I mean that the values of the the last-step (scf) calculation  are significantly different from those of second-step calculation (vc-relax) from bottom.  Thank you!</div>
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<div class="gmail_quote">&control<br>   calculation = 'vc-relax'<br>!   restart_mode='from_scratch',<br>   prefix='graphite',<br>   tstress = .true.<br>   tprnfor = .true.<br>    pseudo_dir   = "/home/wangvei/works/quantum-espresso/pseudo",<br>
    outdir       = "./",<br>    disk_io  = 'none'<br>    forc_conv_thr = 1.0e-3<br>/<br>&system<br>    ibrav           = 4<br>    celldm(1)       = 4.68<br>    celldm(3)       = 2.70<br>    nat             = 4<br>
    ntyp            = 1<br>    occupations = "smearing",<br>    smearing    = "gaussian",<br>    degauss     = 0.002D0,<br>    ecutwfc         = 40.0<br>    ecutrho         = 200<br>!    input_dft       = 'vdw1'<br>
/<br>&electrons<br>    conv_thr        = 1.0d-8<br>/<br>&ions<br>/<br>&cell<br>    press_conv_thr  = 0.5D0<br>    press           = 0.D0<br>    cell_dynamics   = 'bfgs'<br>/<br>ATOMIC_SPECIES<br>C   12.00   C.pbe-paw_kj.UPF<br>
ATOMIC_POSITIONS {crystal}<br> C     0.00000   0.00000   0.25000<br> C     0.00000   0.00000   0.75000<br> C     0.33333   0.66667   0.25000<br> C     0.66667   0.33333   0.75000<br>K_POINTS automatic<br>9 9 4 0 0 0</div>

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<div class="gmail_quote">On 2 July 2011 01:43, Vikas Varshney <span dir="ltr"><<a href="mailto:vv0210@gmail.com">vv0210@gmail.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">Did you update the cell dimensions correctly? For example, if your<br>celldm(1) and celldm(3) before relax are a and c. Lets say after<br>
relax, they become 1.1a and 1.2c. In the final scf calculation, new a<br>should be 1.1a and and new c shsould be (1.2/1.1)*c.<br><br>I dont know if this is the case but just wanted to tell that. Not much<br>help can be done until more input is provided.<br>
<br>Hope this helps<br>Vikas<br>
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<div class="h5"><br><br>On Fri, Jul 1, 2011 at 12:37 PM, WANG Wei <<a href="mailto:wonvein@gmail.com">wonvein@gmail.com</a>> wrote:<br>> Dear QE users,<br>><br>> Why are the total energy and press of the final step of vc-relax<br>
> calculation different from those of the scf calculation using the same<br>> structure?  Especially for the values of press, what makes this great<br>> difference between the final step of vc-relax calculation and the final scf<br>
> calculation (after the vc-relax calculation)?<br>><br>> (1) For the final step of vc-relax calculation, the press and total energy<br>> are:<br>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>> !    total energy              =     -73.74310183 Ry<br>
><br>>           total   stress  (Ry/bohr**3)                   (kbar)     P=<br>> -0.03<br>>   -0.00000009   0.00000001   0.00000000         -0.01      0.00      0.00<br>>    0.00000001  -0.00000008   0.00000000          0.00     -0.01      0.00<br>
>    0.00000000   0.00000000  -0.00000048          0.00      0.00     -0.07<br>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>><br>> (2) For the final scf calculations, the press and total energy are:<br>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
> !    total energy              =     -74.60031750 Ry<br>><br>>           total   stress  (Ry/bohr**3)                   (kbar)     P=<br>> 638.94<br>>    0.00760001  -0.00000151   0.00000000       1118.00     -0.22      0.00<br>
>   -0.00000151   0.00759826   0.00000000         -0.22   1117.74      0.00<br>>    0.00000000   0.00000000  -0.00216804          0.00      0.00   -318.93<br>> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>><br>> Regards,<br>
> WANG<br>><br></div></div>> _______________________________________________<br>> Pw_forum mailing list<br>> <a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>> <a href="http://www.democritos.it/mailman/listinfo/pw_forum" target="_blank">http://www.democritos.it/mailman/listinfo/pw_forum</a><br>
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