<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">No need to post twice the same message ...<div>Don't now about your specific system, but it is not unusual that DFT overestimate binding energies (less so for PBE than LDA)</div><div>Please, do not forget to sign your posts, including your affiliation</div><div>SB</div><div><br><div><div>On Aug 31, 2009, at 8:37 PM, udayagiri sai babu wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi all<br>i am claculating cohesive energy of V using pwscf but i got -8.15 ev/atom against an experimental value of 5.3 ev/atom which is almost 50% off can anybody say what is going wrong with the calculation. the method i used is calculate the total energy of a bcc crystal with 1 atom and deduct the energy of isolated atom from it. the following input files are for finding the total energy for isolated atom and the atom in the crystal. Please tell me if my methodology is wrong.<br> <br><b>cohesive energy=E per atom (in the crystal)-E per atom (isolated)</b><br><br><b>input file for finding the total energy of an isolated atom</b><br><br>&control<br>calculation = 'scf',<br>restart_mode='from_scratch',<br> outdir='/home/sai/temp',<br>prefix='vanadium'<br>pseudo_dir='/home/sai/<div id=":19t" class="ii gt">softwares/espresso-4.0.1/pseudo/',<br>tstress = .TRUE.,<br>tprnfor = .TRUE.,<br>/<br>&system<br> ibrav=1<br>celldm(1)=30,<br> nat=1,<br>ntyp=1<br>ecutwfc=25,<br>ecutrho=100,<br>occupations='smearing',<br>smearing='mv',<br>degauss=0.010000<br>/<br>&electrons<br>conv_thr=1.D-8,<br>diagonalization='david',<br> mixing_mode='plain',<br> mixing_beta= 0.3<br>/<br>ATOMIC_SPECIES<br>V 50.9415 V.pbe-n-van.UPF<br>ATOMIC_POSITIONS (crystal)<br>V 0.00000000 0.00000000 0.00000000<br>K_POINTS {automatic}<br>1 1 1 0 0 0<br><br><b>input file for finding the total energy of the atom in the crystal</b><br> <br>&control<br>calculation = 'scf',<br>restart_mode='from_scratch',<br>outdir='/home/sai/temp',<br>prefix='vanadium'<br>pseudo_dir='/home/sai/softwares/espresso-4.0.1/pseudo/',<br> tstress = .TRUE.,<br>tprnfor = .TRUE.,<br>/<br>&system<br>ibrav=3<br>celldm(1)=5.654,<br>nat=1,<br>ntyp=1<br>ecutwfc=25,<br>ecutrho=100,<br>occupations='smearing',<br>smearing='mv',<br>degauss=0.010000<br> /<br>&electrons<br>conv_thr=1.D-8,<br>diagonalization='david',<br>mixing_mode='plain',<br>mixing_beta= 0.3<br>/<br>ATOMIC_SPECIES<br>V 50.9415 V.pbe-n-van.UPF<br>ATOMIC_POSITIONS (crystal)<br>V 0.00000000 0.00000000 0.00000000<br> K_POINTS {automatic}<br>8 8 8 0 0 0</div> _______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://www.democritos.it/mailman/listinfo/pw_forum<br></blockquote></div><br></div><br><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; 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"><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">---</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">Stefano Baroni - SISSA</span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "> </span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">&</span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "> </span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">DEMOCRITOS National Simulation Center - Trieste</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "><a href="http://stefano.baroni.me">http://stefano.baroni.me</a> [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; font-size: 12px; "><br style="font-size: 12px; "></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; font-size: 12px; "><span class="Apple-style-span" style="font-size: 14px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">La morale est une logique de l'action comme la logique est une morale de la pensée - Jean Piaget</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "><br></span></font></div></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">Please, if possible, don't</span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "> </span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">send me MS Word or PowerPoint attachments</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; ">Why? See:</span></font><font class="Apple-style-span" size="3"><span class="Apple-style-span" style="font-size: 12px; "> </span></font><font class="Apple-style-span" color="#0023E9" size="3"><span class="Apple-style-span" style="font-size: 12px; "><a href="http://www.gnu.org/philosophy/no-word-attachments.html">http://www.gnu.org/philosophy/no-word-attachments.html</a></span></font></div><div><font class="Apple-style-span" color="#0023E9" size="3"><span class="Apple-style-span" style="font-size: 12px; "><br class="webkit-block-placeholder"></span></font></div></div></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"> </div><br></body></html>