Thank you very much sir, now I have gotten a cl ear picture of how to calculate celldm(4)-celldm(6)<div id="yMail_cursorElementTracker_0.5131955565884709"><br></div><div id="yMail_cursorElementTracker_0.5131955565884709">Now my question is that  in the case where celldm(4)=0.00</div><div id="yMail_cursorElementTracker_0.5131955565884709"> for monoclinic structure can we say the crystal structure is similar or same as that of orthorhombic sinc<br> <br> <blockquote style="margin: 0 0 20px 0;"> <header style="font-family:Roboto, sans-serif; color:#6D00F6;"> <div>On Mon, Feb 22, 2016 at 9:54, Giovanni Cantele</div><div><giovanni.cantele@spin.cnr.it> wrote:</div> </header> <div style="padding: 10px 0 0 20px; margin: 10px 0 0 0; border-left: 1px solid #6D00F6;"> <div id="msgSandbox_AMa2FimIAAAMkVsrMqQehIIzT8xI_TEXT" class="msgSandbox" style="padding: 1.5em 0.5em 0.5em 1.2em; word-wrap: break-word;"><div class="yQTDBase yqt2460697886" id="yqtfd31924"><br clear="none">> On 20 Feb 2016, at 20:34, Ridwan Agbaoye <<a shape="rect" ymailto="mailto:agbaoyeridwan@yahoo.com" href="javascript:return">agbaoyeridwan@yahoo.com</a>> wrote:<br clear="none">> <br clear="none">> Please I need clarification on how to compute celldm(4), celldm(5) and celldm(6) for ibrav 12, 13 and 14 <br clear="none">> <br clear="none">> I have conflicting opinion on how it should be calculated though it is stated as for ibrav =12 and 13 celldm(4)=cos(ab),for ibrav 14 celldm(4)=cos(bc), celldm(5)=cos(ac)and celldm(6)=(ab).  Although cos(ab) is the cosine of angle between lattice parameters a and b as stated in INPUT_PW.HTML of quantum espresso<br clear="none">> <br clear="none">> Please I need clarifications<br clear="none">> <br clear="none">> Agbaoye Ridwan Olamide<br clear="none">> Federal University of Agriculture, Abeokuta<br clear="none">> M.Sc. (in view)</div><br clear="none">> _______________________________________________<br clear="none">> Pw_forum mailing list<br clear="none">> <a shape="rect" ymailto="mailto:Pw_forum@pwscf.org" href="javascript:return">Pw_forum@pwscf.org</a><br clear="none">> <a shape="rect" href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank">http://pwscf.org/mailman/listinfo/pw_forum</a><br clear="none"><br clear="none"><br clear="none">Example for ibrav=12<br clear="none"><br clear="none">cosAB = cosine of the angle between axis a and b (gamma)<br clear="none"><br clear="none">So if you know the lattice vector coordinates, that is, a=(ax,ay,az) and b=(bx,by,bz), just calculate <br clear="none">cosAB = a . b / ( |a| |b| )<br clear="none">where a . b = dot product of a and b = ax bx + ay by + az bz<br clear="none">|a| = length of vector a = sqrt( ax^2 + ay^2 + az^2 ) and same for |b|.<br clear="none"><br clear="none">Instead, if you know, directly gamma, just compute cos( gamma ).<br clear="none"><br clear="none">Similar consideration apply to cos(bc) and cos(ac) for the other lattices.<br clear="none"><br clear="none">Giovanni<br clear="none"><br clear="none">-- <br clear="none"><br clear="none">Giovanni Cantele, PhD<br clear="none">CNR-SPIN<br clear="none">c/o Dipartimento di Fisica<br clear="none">Universita' di Napoli "Federico II"<br clear="none">Complesso Universitario M. S. Angelo - Ed. 6<br clear="none">Via Cintia, I-80126, Napoli, Italy<br clear="none">e-mail: <a shape="rect" ymailto="mailto:giovanni.cantele@spin.cnr.it" href="javascript:return">giovanni.cantele@spin.cnr.it</a><br clear="none">Phone: +39 081 676910<br clear="none">Skype contact: giocan74<br clear="none"><br clear="none">ResearcherID: <a shape="rect" href="http://www.researcherid.com/rid/A-1951-2009" target="_blank">http://www.researcherid.com/rid/A-1951-2009</a><br clear="none">Web page: <a shape="rect" href="http://people.na.infn.it/~cantele" target="_blank">http://people.na.infn.it/~cantele</a><br clear="none"><br clear="none"><br clear="none"><br clear="none">_______________________________________________<br clear="none">Pw_forum mailing list<br clear="none"><a shape="rect" ymailto="mailto:Pw_forum@pwscf.org" href="javascript:return">Pw_forum@pwscf.org</a><br clear="none"><a shape="rect" href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank">http://pwscf.org/mailman/listinfo/pw_forum</a><div class="yQTDBase yqt2460697886" id="yqtfd88375"><br clear="none"></div></div> </div> </blockquote></div>