Dear Ali :<br><br> What the force thread you set for the unit cell ? i.e,<br>forc_conv_thr . The values you posted here are quite close to the default setting , 1.0D-3. Therefore, You can run ion-relaxation to satisfy yourself, whichi i think is not a computation burden.<br>
<br>If you have built your unitcell system with satisfied accuaray, there is no reason to make cell relation for a supercell. <br><br><br>Regards,<br><div class="gmail_quote">On Thu, Aug 20, 2009 at 11:11 PM, ali kazempour <span dir="ltr"><<a href="mailto:kazempoor2000@yahoo.com">kazempoor2000@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td style="font-family: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-size: inherit; line-height: inherit; font-size-adjust: inherit; font-stretch: inherit;" valign="top">
Dear<br>I use vc-relax to optimize the lattice constant and also the position for bulk. After I make supercell with these optimized value and run a scf with similar value as bulk. But the force as I listed below for some atom is relatively more than other. Is it good for force or should I do again vc-relax for supercell?<br>
Forces acting on atoms (Ry/au):<br><br> atom 1 type 1 force = 0.00000000 0.00000000 0.00000000<br> atom 2 type 1 force = 0.00000000 0.00000000 0.00000000<br> atom 3 type 1 force = 0.00000000 0.00000000
0.00000000<br> atom 4 type 1 force = 0.00000000 0.00000000 0.00000000<br> atom 5 type 1 force = 0.00000000 0.00000000 0.00020439<br> atom 6 type 1 force = 0.00000000 0.00000000 0.00020567<br>
atom 7 type 1 force = 0.00000000 0.00000000 0.00020567<br> atom 8 type 1 force = 0.00000000 0.00000000 0.00020315<br> atom 9 type 1 force
= 0.00000000 0.00000000 -0.00020439<br> atom 10 type 1 force = 0.00000000 0.00000000 -0.00020567<br> atom 11 type 1 force = 0.00000000 0.00000000 -0.00020567<br> atom 12 type 1 force = 0.00000000 0.00000000 -0.00020315<br>
atom 13 type 1 force = -0.00000152 -0.00000152 -0.00019723<br> atom 14 type 1 force = 0.00000136 -0.00000136 -0.00019719<br> atom 15 type 1 force
= -0.00000136 0.00000136 -0.00019719<br> atom 16 type 1 force = 0.00000152 0.00000152 -0.00019723<br> atom 17 type 1 force = -0.00000186 -0.00000186 0.00000000<br> atom 18 type 1 force = 0.00000137 -0.00000137 0.00000000<br>
atom 19 type 1 force = -0.00000137 0.00000137 0.00000000<br> atom 20 type 1 force = 0.00000186 0.00000186 0.00000000<br> atom 21 type 1
force = -0.00000152 -0.00000152 0.00019723<br> atom 22 type 1 force = 0.00000136 -0.00000136 0.00019719<br> atom 23 type 1 force = -0.00000136 0.00000136 0.00019719<br> atom 24 type 1 force = 0.00000152 0.00000152 0.00019723<br>
atom 25 type 2 force = -0.00126659 -0.00126659 0.00000000<br> atom 26 type 2 force = -0.00126600 -0.00126594 0.00000000<br> atom 27 type 2
force = -0.00126594 -0.00126600 0.00000000<br> atom 28 type 2 force = -0.00126811 -0.00126811 0.00000000<br> atom 29 type 2 force = -0.00120604 -0.00120604 0.00011420<br> atom 30 type 2 force = -0.00120546 -0.00120538 0.00011547<br>
atom 31 type 2 force = -0.00120538 -0.00120546 0.00011547<br> atom 32 type 2 force = -0.00120536 -0.00120536 0.00011440<br> atom 33 type 2 force
= -0.00120604 -0.00120604 -0.00011420<br> atom 34 type 2 force = -0.00120546 -0.00120538 -0.00011547<br> atom 35 type 2 force = -0.00120538 -0.00120546 -0.00011547<br> atom 36 type 2 force = -0.00120536 -0.00120536 -0.00011440<br>
atom 37 type 2 force = 0.00126811 0.00126811 0.00000000<br> atom 38 type 2 force = 0.00126594 0.00126600 0.00000000<br> atom 39 type 2 force
= 0.00126600 0.00126594 0.00000000<br> atom 40 type 2 force = 0.00126659 0.00126659 0.00000000<br> atom 41 type 2 force = 0.00120536 0.00120536 0.00011440<br> atom 42 type 2 force = 0.00120538 0.00120546 0.00011547<br>
atom 43 type 2 force = 0.00120546 0.00120538 0.00011547<br> atom 44 type 2 force = 0.00120604 0.00120604 0.00011420<br>
atom 45 type 2 force = 0.00120536 0.00120536 -0.00011440<br> atom 46 type 2 force = 0.00120538 0.00120546 -0.00011547<br> atom 47 type 2 force = 0.00120546 0.00120538 -0.00011547<br>
atom 48 type 2 force = 0.00120604 0.00120604 -0.00011420<br> atom 49 type 2 force = -0.00120811 0.00120812 -0.00010994<br> atom 50 type 2 force = -0.00120609 0.00120609 -0.00011010<br>
atom 51 type 2 force = -0.00120474 0.00120474 -0.00011334<br> atom 52 type 2 force = -0.00120812 0.00120811 -0.00010994<br> atom 53 type 2 force = -0.00126901 0.00126929 0.00000000<br>
atom 54 type 2 force = -0.00126831 0.00126831 0.00000000<br> atom 55 type 2 force = -0.00126875 0.00126875 0.00000000<br> atom 56 type 2 force = -0.00126929 0.00126901 0.00000000<br>
atom 57 type 2 force = -0.00120811 0.00120812 0.00010994<br> atom 58 type 2 force = -0.00120609 0.00120609 0.00011010<br> atom 59 type 2 force = -0.00120474 0.00120474 0.00011334<br>
atom 60 type 2 force = -0.00120812 0.00120811 0.00010994<br> atom 61 type 2 force = 0.00120812 -0.00120811 -0.00010994<br> atom 62 type 2 force = 0.00120474 -0.00120474 -0.00011334<br>
atom 63 type 2 force = 0.00120609 -0.00120609 -0.00011010<br> atom 64 type 2 force = 0.00120811 -0.00120812 -0.00010994<br> atom 65 type 2 force = 0.00126929 -0.00126901 0.00000000<br>
atom 66 type 2 force = 0.00126875 -0.00126875 0.00000000<br> atom 67 type 2 force = 0.00126831 -0.00126831 0.00000000<br> atom 68 type 2 force = 0.00126901 -0.00126929 0.00000000<br>
atom 69 type 2 force = 0.00120812 -0.00120811 0.00010994<br> atom 70 type 2 force = 0.00120474 -0.00120474 0.00011334<br> atom 71 type 2 force = 0.00120609 -0.00120609 0.00011010<br>
atom 72 type 2 force = 0.00120811 -0.00120812 0.00010994<br><br> Total force = 0.012066 Total SCF correction = 0.000257<br><br><br> entering subroutine stress ...<br><br> total stress
(Ry/bohr**3) (kbar) P= -90.60<br> -0.00062585 0.00000003 0.00000000 -92.07 0.00 0.00<br> 0.00000003 -0.00062585 0.00000000 0.00 -92.07 0.00<br> 0.00000000 0.00000000 -0.00059589 0.00 0.00 -87.66<br>
<br>thanks a lot<br><br>Ali Kazempour<br>
Physics department, Isfahan University of Technology<br>
84156 Isfahan, Iran. Tel-1: +98 311 391 3733<br>
Fax: +98 311 391 2376 Tel-2: +98 311 391 2375</td></tr></tbody></table><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Hai-Ping Lan <br>Department of Electronics ,<br>Peking University , Bejing, 100871<br><a href="mailto:lanhaiping@gmail.com">lanhaiping@gmail.com</a>, <a href="mailto:hplan@pku.edu.cn">hplan@pku.edu.cn</a><br>