<div> </div><div>Thank you. </div><div> </div><div>I did not notice the unit difference in pw.x and cp.x. </div><div> </div><div>But it seems that the energies that both codes obtained agree well. I pasted the results in the following. The first one is the result from vc-relax operated on one unit cell, the total energy is -358.1 Ry, this is very close to my original setup with scf calculation. The second one is from cp.x operated on 2 by 2 by 2 supercell, with fixed atom positions(ion and cell_dynamics are set to 'none'), the energy is -1410 au==-2820 Ry. I don't know whether this is a big difference, but I cannot find an obvious error, but the pressure is quite high, like100GPa, and it is sensitive to the setup especially $electron part. </div>
<div> </div><div>I don't quite get your point about the default positions of atoms in pw and cp. In both codes, I used 'crystal', and in the supercell, all the ratios are in reference to this cubic supercell. I don't think the atom positions have much problem from the result.</div>
<div> </div><div>Thank you!</div><div>Tian</div><div> </div><div>---------------------------------------------------------------------------------------------</div><div>pw.x</div><div>------------------------------------------------------------------------------------------</div>
<div>total energy = -358.09688074 Ry<br> Harris-Foulkes estimate = -358.09688074 Ry<br> estimated scf accuracy < 9.1E-14 Ry</div><div> The total energy is the sum of the following terms:</div>
<div> one-electron contribution = -98.88874403 Ry<br> hartree contribution = 94.24811082 Ry<br> xc contribution = -<a href="tel:60.23256770" target="_blank" value="+16023256770">60.23256770</a> Ry<br>
ewald contribution = -293.22367983 Ry</div>
<div> convergence has been achieved in 27 iterations</div><div> Forces acting on atoms (Ry/au):</div><div> atom 1 type 2 force = 0.00000000 0.00000000 0.00000000<br> atom 2 type 2 force = 0.00000000 0.00000000 -0.00000000<br>
atom 3 type 2 force = 0.00000000 -0.00000000 -0.00000000<br> atom 4 type 2 force = -0.00000000 0.00000000 -0.00000000<br> atom 5 type 1 force = 0.00000000 0.00000000 0.00000000<br>
atom 6 type 1 force = 0.00000000 0.00000000 0.00000000</div><div> Total force = 0.000000 Total SCF correction = 0.000000</div><div><br> entering subroutine stress ...</div><div> total stress (Ry/bohr**3) (kbar) P= -0.08<br>
-0.00000054 0.00000000 0.00000000 -0.08 0.00 0.00<br> 0.00000000 -0.00000054 0.00000000 0.00 -0.08 0.00<br> 0.00000000 0.00000000 -0.00000054 0.00 0.00 -0.08<br>
</div><div> bfgs converged in 5 scf cycles and 2 bfgs steps<br> (criteria: energy < 0.10E-03, force < 0.10E-02, cell < 0.50E+00)</div><p> End of BFGS Geometry Optimization</p><p> Final enthalpy = -358.0968807430 Ry<br>
Begin final coordinates<br> new unit-cell volume = 774.49676 a.u.^3 ( 114.76858 Ang^3 )</p><p>CELL_PARAMETERS (alat= 9.15690000)<br> 1.002900997 0.000000000 0.000000000<br> 0.000000000 1.002900997 0.000000000<br>
0.000000000 0.000000000 1.002900997</p><div>ATOMIC_POSITIONS (crystal)<br>Ag 0.250000000 0.250000000 0.250000000<br>Ag 0.750000000 0.750000000 0.250000000<br>Ag 0.250000000 0.750000000 0.750000000<br>
Ag 0.750000000 0.250000000 0.750000000<br>O 0.000000000 0.000000000 0.000000000<br>O 0.500000000 0.500000000 0.500000000<br>End final coordinates</div><div><br>------------------------------------------------------------------------------------</div>
<div>cp.x<br>------------------------------------------------------------------------------------</div><div>Partial temperatures (for each ionic specie)<br> Species Temp (K) Mean Square Displacement (a.u.)<br> 1 0.00 0.0000<br>
2 0.00 0.0000</div><div> nfi ekinc temph tempp etot enthal econs econt vnhh xnhh0 vnhp xnhp0<br> 100 0.00092 0.0 0.0 -1431.80272 -1431.80272 -1431.80272 -1431.80180 0.0000 0.0000 0.0000 0.0000</div>
<div> writing restart file: ./Ag2O_51.save<br> restart file written in 39.227 sec.</div><div> </div><div> Averaged Physical Quantities<br> accomulated this run<br> ekinc : 7.61699 7.61699 (AU)<br>
ekin : 374.63650 374.63650 (AU)<br> epot : -1373.54937 -1373.54937 (AU)<br> total energy : -1410.67335 -1410.67335 (AU)<br> temperature : 0.00000 0.00000 (K )<br>
enthalpy : -1410.67335 -1410.67335 (AU)<br> econs : -1410.67335 -1410.67335 (AU)<br> pressure : 93.03124 93.03124 (Gpa)<br> volume : 6148.60237 6148.60237 (AU)<br>
<br></div><div class="gmail_quote">On Thu, Sep 13, 2012 at 1:22 AM, Paolo Giannozzi <span dir="ltr"><<a href="mailto:giannozz@democritos.it" target="_blank">giannozz@democritos.it</a>></span> wrote:<br><blockquote style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid" class="gmail_quote">
<div>On Wed, 2012-09-12 at 15:33 -0700, Tian Lan wrote:<br>
<br>
> I expected a good structure from scf calculation should more or less<br>
> agree with the MD run.<br>
<br>
</div>it does. First of all, you should verify that you can get the same<br>
energy (within numerical noise, and not forgetting the Ha to Ry<br>
conversion) with pw.x and cp.x (beware the different defaults<br>
for atomic positions in input). In the latter case, just perform<br>
an electronic minimization at fixed atoms.<br>
<span><font color="#888888"><br>
P.<br>
--<br>
Paolo Giannozzi, IOM-Democritos and University of Udine, Italy<br>
<br>
<br>
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</font></span></blockquote></div><br><br clear="all"><br>-- <br>Lan, Tian<br>
Ph.D. Candidate, Department of Applied Physics and Materials Science<br>
California Institute of Technology,<br>
Caltech M/C 138-78, Pasadena, CA, 91125<br>