<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">Dear Osman Baris</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif"> </DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">I'm working on zigzag carbon nanotube. my problem is that my system doesn't converg , I don't know the steps in order that the parameters should be optimized. I don't know the mixing beta should be optimized or not! I have to mention that there is overlap in Davidson diagonalization.</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">Meisam Aghtar</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">M.Sc</DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">Physics Department of Kashan university. <BR><BR></DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman, new york, times, serif">----- Original Message ----<BR>From: "mbaris@metu.edu.tr" <mbaris@metu.edu.tr><BR>To: PWSCF Forum <pw_forum@pwscf.org><BR>Sent: Sunday, December 23, 2007 3:20:24 PM<BR>Subject: Re: [Pw_forum] optimizing pw input parameters<BR><BR>Dear Meisam Aghtar,<BR><BR>> which parameters should be optimized sequencly in a scf runing? the <BR>> parameters are celldm(1),ecutwfc, ecutrho,mixing-beta and K-points.<BR><BR>All of them.<BR><BR>> another problem is that for optimizing the ecutwfc the system <BR>> converges for some numbers and it doesn't for some more. I have to <BR>> mention that there is overlap in davidson diagonalization.<BR>><BR><BR>yes, they have such bad manners.<BR><BR><BR><BR><BR>As previously mentioned in the forum, observables such as celldm(1) <BR>converge much more rapidly than total energy. I do not know about your <BR>specific
problem, but what I do for in the project I am currently <BR>working on is this: I have written a small script that scans a given <BR>parameter range (ecutwfc, ecutrho, etc) and minimizes celldm(1) for the <BR>specific set using a golden search algorithm, then, plotting the <BR>results (for example celldm(1) vs ecutwfc for different k-point sets), <BR>I decide which set to use.<BR><BR>why do you want to alter mixing beta? Do you have convergence problems?<BR><BR>and for ecutrho, it is generally safe to use 10xecutwfc, (remember, I <BR>do not know what you are working on, and assuming something <BR>straightforward). Please dig more about how ecutrho is used in the <BR>code. and it is better to add your affiliation after a post.<BR><BR>Merry X-mas everyone!<BR><BR>Osman Baris Malcioglu<BR>Ph.D. Candidate<BR>METU Physics<BR>Ankara, Turkey<BR><BR><BR><BR><BR><BR><BR><BR>_______________________________________________<BR>Pw_forum mailing
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