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--></style></head><body lang=EN-US link=blue vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'>Hello <o:p></o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'>In ATOMIC_POSITIONS you need to specify the units that you are using for the coordinates, if you don’t put anything he program assumes alat units and puts the 2 atoms very far apart. <o:p></o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'>If you actually wanted compute the two separated atoms specifying startingwfc=’random’ in the &electrons name list may help. In this case I would also chose calculation=’scf’ in &control. <o:p></o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'>Regards - Pietro <o:p></o:p></span></span></p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><p class=MsoNormal>Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> for Windows 10</p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:poojavyas595@gmail.com">Pooja Vyas</a><br><b>Sent: </b>Friday, June 26, 2020 8:12 AM<br><b>To: </b><a href="mailto:users@lists.quantum-espresso.org">Quantum ESPRESSO users Forum</a><br><b>Subject: </b>[QE-users] Energy of isolated atom of CaO</p></div><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p><div><div><p class=MsoNormal>Dear users,</p></div><div><p class=MsoNormal>I want to calculate cohesive energy of CaO. I'm using cluster_example/PW which uses assume_isolated = 'martyna_tuckerman' . Following is my input script:</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>#!/bin/sh<br>for a in 30<br>do<br>cat > ${a}.in << EOF<br>&CONTROL<br> calculation = 'relax'<br> prefix = "${a}",<br> pseudo_dir = "/home/user/pv/cohesive/pseudo/",<br> outdir = "/home/user/pv/cohesive/",<br>/<br>&SYSTEM<br> ibrav = 1,<br> celldm(1) = $a,<br> nat = 2,<br> ntyp = 2,<br> ecutwfc = 100.D0,<br> assume_isolated = 'martyna-tuckerman'<br>/<br>&ELECTRONS<br> conv_thr = 1.D-8,<br> mixing_beta = 0.7D0,<br>/<br>&IONS<br>/<br>ATOMIC_SPECIES<br>Ca 40.078 Ca.pbe-nsp-van.UPF<br>O 15.999 O.pbe-van_ak.UPF<br>ATOMIC_POSITIONS <br>Ca 0.0 0.0 0.0<br>O 0.5 0.5 0.5<br>K_POINTS Gamma<br><br>EOF<br><br>mpirun -np 40 -machinefile x1 /apps/codes/qe/6.4/bin/pw.x < ${a}.in > ${a}.out<br>done<br>done</p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>My lattice constant is around 8 a.u , so I assumed the box size to be 3 times of it. But when I run the script, the convergence was not achieved even after 100 iterations. Then I tried to take small box size of about 16 bohr. That too didn't work. Then I even tried reducing ecutwfc and mixing_beta..but same error was obtained. Can anyone suggest what can I do to resolve the issue?</p></div><div><p class=MsoNormal>Any kind of help is appreciated.</p></div></div><p class=MsoNormal>Thanks and regards.</p><p class=MsoNormal><span class=DefaultFontHxMailStyle><span style='font-size:12.0pt'><o:p> </o:p></span></span></p></div></body></html>