<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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