<html><head><base href="x-msg://322/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Mar 5, 2010, at 2:53 PM, Elie Moujaes wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" 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="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div>0.2 0.0 0.0 1.0<br class="Apple-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>
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