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Thanks for the reply. It was really helpful<BR>
<BR>
Regards,<BR>
<BR>
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From: giovanni.cantele@na.infn.it<BR>Date: Fri, 5 Mar 2010 15:06:07 +0100<BR>To: pw_forum@pwscf.org<BR>Subject: Re: [Pw_forum] crystal or tpiba_b<BR><BR><BASE><BR>
<DIV>
<DIV>On Mar 5, 2010, at 2:53 PM, Elie Moujaes wrote:</DIV><BR class=ecxApple-interchange-newline>
<BLOCKQUOTE><SPAN class=ecxApple-style-span style="WORD-SPACING: 0px; FONT: medium Helvetica; TEXT-TRANSFORM: none; TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate">
<DIV class=ecxhmmessage style="FONT-SIZE: 10pt; FONT-FAMILY: Verdana">Dear all,<BR> <BR>I read that if we are trying to calculate the band structure, it is better to use {tpiba_b} in ATOMIC POSITIONS rather than {crystal}. Is the only difference related to the points that will be plotted at the end because one is wrt to cartesian and the other relative to crystallographic axes?<BR> <BR> </DIV></SPAN></BLOCKQUOTE><BR></DIV>
<DIV>I never used tpiba_b or crystal_b. Nevertheless, by reading the Doc/INPUT_PW.txt I understand that it is not a matter of tpiba vs crystal, but of tpiba_b/crystal_b vs tpiba/crystal. Using either tpiba or crystal, you must specify the full list of k-points you want to show in your band structure plot. On the contrary, the *_b options (tpiba_b/crystal_b) allow to specify, for each given line in the Brillouin zone, only the 1st and last point, together with the number of points along that line.</DIV>
<DIV><BR></DIV>
<DIV>As an example, you can replace</DIV>
<DIV style="TEXT-ALIGN: left">K_POINTS {crystal}</DIV>
<DIV style="TEXT-ALIGN: left">5</DIV>
<DIV>0.0 0.0 0.0 1.0</DIV>0.1 0.0 0.0 1.0<BR>
<DIV><SPAN class=ecxApple-style-span style="WORD-SPACING: 0px; FONT: medium Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate"><SPAN class=ecxApple-style-span style="WORD-SPACING: 0px; FONT: medium Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate">
<DIV style="WORD-WRAP: break-word"><SPAN class=ecxApple-style-span style="WORD-SPACING: 0px; FONT: medium Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate">
<DIV>0.2 0.0 0.0 1.0<BR class=ecxApple-interchange-newline>0.3 0.0 0.0 1.0</DIV>
<DIV>0.4 0.0 0.0 1.0</DIV>
<DIV>0.5 0.0 0.0 1.0</DIV>
<DIV>with</DIV>
<DIV>
<DIV style="TEXT-ALIGN: left">K_POINTS {crystal_b}</DIV>
<DIV style="TEXT-ALIGN: left">2</DIV>
<DIV>0.0 0.0 0.0 5.0</DIV>0.5 0.0 0.0 5.0</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>The choice of either crystal_b or tpiba_b is instead driven by in which coordinate system (crystallographic axes or cartesian, respectively) you find easier to write the</DIV>
<DIV>components of the k-points you need.</DIV>
<DIV><BR></DIV>
<DIV>Giovanni</DIV>
<DIV><BR></DIV>
<DIV>--</DIV>
<DIV><BR></DIV>
<DIV>
<DIV>Giovanni Cantele, PhD</DIV>
<DIV>CNR-SPIN and Dipartimento di Scienze Fisiche</DIV>
<DIV>Universita' di Napoli "Federico II"</DIV>
<DIV>Complesso Universitario M. S. Angelo - Ed. 6</DIV>
<DIV>Via Cintia, I-80126, Napoli, Italy</DIV>
<DIV>Phone: +39 081 676910 - Fax: +39 081 676346</DIV>
<DIV>Skype contact: giocan74</DIV>
<DIV><BR></DIV>
<DIV>ResearcherID: <A href="http://www.researcherid.com/rid/A-1951-2009">http://www.researcherid.com/rid/A-1951-2009</A></DIV>
<DIV>Web page: <A href="http://people.na.infn.it/~cantele">http://people.na.infn.it/~cantele</A></DIV>
<DIV> <A href="http://www.nanomat.unina.it/">http://www.nanomat.unina.it</A></DIV></DIV></SPAN></DIV></SPAN></SPAN></DIV><BR> <br /><hr />Got a cool Hotmail story? <a href='http://clk.atdmt.com/UKM/go/195013117/direct/01/' target='_new'>Tell us now</a></body>
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