No. I didn't relax the molecule. As a matter of fact, I got this structure from want code's self test, and thought it was already relaxed-.-<br>I'll relax it later and see if good things happen.<br><br>Best,<br>-- <br>Jin Zhang
<br>Dep. of Physics,<br>Peking Univ.<br><br><div><span class="gmail_quote">On 11/20/06, <b class="gmail_sendername">degironc</b> <<a href="mailto:degironc@sissa.it" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
degironc@sissa.it</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
did you relaxed the structure ?<br>These are the forces I get with your input [a typical threshold for a<br>structural relaxation is<br>forc_conv_thr REAL ( default = 1.0D-3 ) ].<br>stefano<br><br> Forces acting on atoms (Ry/au):
<br><br> atom 1 type 2 force = -0.06870568 0.00011605 0.00070580<br> atom 2 type 1 force = 0.00057171 -0.00133033 0.00026104<br> atom 3 type 2 force = -0.03470840 0.06008037
0.00060235<br> atom 4 type 1 force = -0.00200170 -0.00052894 -0.00023669<br> atom 5 type 2 force = 0.03477692 0.05989867 -0.00004091<br> atom 6 type 1 force = 0.00029793
0.00027534 -0.00032982<br> atom 7 type 2 force = 0.06862846 -0.00002844 -0.00054894<br> atom 8 type 1 force = -0.00256825 0.00128897 -0.00025706<br> atom 9 type 2 force =
0.03495275
-0.06050673 -0.00040942<br> atom 10 type 1 force = -0.00020204 0.00131722 0.00025463<br> atom 11 type 2 force = -0.03450037 -0.05925204 0.00020053<br> atom 12 type 1 force =
0.00345864 -0.00133014 -0.00020152<br><br> Total force = 0.169286 Total SCF correction = 0.000107<br><br>stefano<br><br><br>Jin Zhang wrote:<br><br>> Dear MMC,<br>><br>> The supercell I used is a simple cubic one (let ibrav=8
<br>> celldim(1,2,3)=20bohr). Because the molecule is isolated, I think the<br>> kpoint sampling should be irrelevant. And I used gamma point for the<br>> calculation.<br>><br>> I increased ecut to 25Ry, and celldim to 30bohr) the number of
<br>> negative modes increase by 9 (to 21modes)!<br>> OMG, there must be sth wrong!<br>> I'll attach my input and see if someone can give some comments.<br>> !-----------------------omega-------------------<br>
> omega( 1) = -123.660534 [THz] = -4124.898815 [cm-1]<br>> omega( 2) = -122.070631 [THz] = -4071.865015 [cm-1]<br>> omega( 3) = -109.408034 [THz] = -3649.483445 [cm-1]<br>> omega( 4) = -
103.611190 [THz] = -3456.120267 [cm-1]<br>> omega( 5) = -100.288151 [THz] = -3345.274863 [cm-1]<br>> omega( 6) = -86.921490 [THz] = -2899.408087 [cm-1]<br>> omega( 7) = -86.648147
[THz] = -
2890.290289 [cm-1]<br>> omega( 8) = -78.536226 [THz] = -2619.703943 [cm-1]<br>> omega( 9) = -63.552993 [THz] = -2119.913758 [cm-1]<br>> omega(10) = -60.437624 [THz] = -2015.995524
[cm-1]<br>> omega(11) = - 59.290658 [THz] = -1977.736621 [cm-1]<br>> omega(12) = -59.022664 [THz] = -1968.797246 [cm-1]<br>> omega(13) = -58.953578 [THz] = -1966.492750 [cm-1]<br>
> omega(14) = -46.326804 [THz] = -1545.306104 [cm-1]<br>> omega(15) = -31.263942 [THz] = -1042.859776 [cm-1]<br>> omega(16) = -31.093207 [THz] = -1037.164629 [cm-1]<br>> omega(17) = -
27.758798 [THz] = -925.939988 [cm-1]<br>> omega(18) = - 27.694407 [THz] = -923.792135 [cm-1]<br>> omega(19) = -24.097859 [THz] = -803.823410 [cm-1]<br>> omega(20) = -20.675736
[THz] = -
689.672916 [cm-1]<br>> omega(21) = -20.064562 [THz] = -669.286187 [cm-1]<br>> omega(22) = 15.218497 [THz] = 507.637805 [cm-1]<br>> omega(23) = 16.277849 [THz] = 542.974191
[cm-1]
<br>> omega(24) = 20.249558 [THz] = 675.457041 [cm-1]<br>> omega(25) = 21.320279 [THz] = 711.172668 [cm-1]<br>> omega(26) = 22.104349 [THz] = 737.326626 [cm-1]<br>> omega(27) =
23.427206 [THz] = 781.452687 [cm-1]<br>> omega(28) = 30.392570 [THz] = 1013.793763 [cm-1]<br>> omega(29) = 43.644315 [THz] = 1455.827328 [cm-1]<br>> omega(30) = 55.006552 [THz] =
1834.833267 [cm-1]<br>> omega(31) = 57.997854 [THz] = 1934.613035 [cm-1]<br>> omega(32) = 61.898591 [THz] = 2064.728462 [cm-1]<br>> omega(33) = 68.862483 [THz] = 2297.020463
[cm-1]<br>> omega(34) = 68.979827 [THz] = 2300.934652 [cm-1]<br>> omega(35) = 69.303015 [THz] = 2311.715098 [cm-1]<br>> omega(36) = 69.697807 [THz] = 2324.884051 [cm-1]<br>
><br>> On 11/19/06, *Miguel Martínez Canales* < <a href="mailto:wmbmacam@lg.ehu.es" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">wmbmacam@lg.ehu.es</a><br>> <mailto:<a href="mailto:wmbmacam@lg.ehu.es" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
wmbmacam@lg.ehu.es</a>>> wrote:<br>><br>> Hi Jin,
<br>><br>> Jin Zhang escribió:<br>> > The thing I cannot understand is, there're 12 negative frequencies<br>> > existing. I know 3 of them are purely translational modes and<br>> another 3
<br>> > are rotational ones. But what about the rest 6? I'm a little<br>> confused<br>> > and hopefully someone can help.<br>> ><br>> > The eigenvals are pasted below and thanks in advance!
<br>> ><br>> > (the result may not be accurate due to a only-15Ry ecut I used,<br>> but it<br>> > should not give out qualitative different result)<br>><br>> For a start, I wouldn't think 15 rydbergs is enough. Have you
<br>> tested the<br>> pseudopotentials for ecut convergence? 25 or 30 would probably be<br>> a better<br>> choice. Anyway, what you probably are missing most in your<br>> calculations is
<br>> k-point sampling convergence. Translational and rotational<br>> frequencies are<br>> a bit too large. What happens if you increase your k-point grid?<br>> Anyway,<br>> don¡t forget to relax your molecule with the new parametres.
<br>><br>> BTW: What kind of cell are you using? I've never done molecular<br>> normal mode<br>> calculations but I guess that in the case of bencene using an<br>> hexagonal<br>> supercell might make sense.
<br>><br>> --<br>> ----------------------------------------<br>> Miguel Martínez Canales<br>> Dto. Física de la Materia Condensada<br>> UPV/EHU<br>> Facultad de Ciencia y Tecnología
<br>> Apdo. 644<br>> 48080 Bilbao (Spain)<br>> Fax: +34 94 601 3500<br>> Tlf: +34 94 601 5437<br>> ----------------------------------------<br>><br>> "The problem with Renault is that they dont have
<br>> the skills to convince FIA that the mass damper<br>> is just a brake cooler."<br>><br>> Annonymous<br>><br>> _______________________________________________<br>> Pw_forum mailing list
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</a><br>><br>><br>><br>><br>> --<br>> Jin Zhang<br>> Dep. of Physics,<br>> Peking Univ.<br><br><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
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