<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">cos(ab) means cosine of the angle between lattice AXIS a and lattice AXIS b, so xcrysden gives you the correct view<div class=""><br class=""></div><div class="">see also Doc/INPUT_PW.txt at the description of the variable A, B, C, cosAB, cosAC, cosBC</div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 21 Dec 2015, at 12:16, Ridwan Agbaoye <<a href="mailto:agbaoyeridwan@yahoo.com" class="">agbaoyeridwan@yahoo.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><div style="background-color: rgb(255, 255, 255); font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 16px;" class=""><div id="yui_3_16_0_1_1450695527382_7752" class="">Good day everyone </div><div id="yui_3_16_0_1_1450695527382_7752" class="">I need some help with clarification on celldm(4)=cos(ab) </div><div id="yui_3_16_0_1_1450695527382_7752" class=""><br class=""></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">Does cos(ab) mean the cosine of angle between lattice parameter a and b </div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">or it means the cosine of the product of the lattice parameter a and b that is cosine(lattice parameter a*lattice parameter b)</div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class=""><br class=""></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">when i view my input file using xcrysden it looks like a cubic structure when i used celldm(4)=cos(ab)=0 since angle between a and b is 90 degree</div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class=""><br class=""></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">but looked like a monoclinic structure when i used cosine(lattice parameter a*lattice parameter b)</div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class=""><br class=""></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">Am i getting the cos(ab) wrong</div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class=""><br class=""></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class="">Many Thanks to everyone on this forum </div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr" class=""><br class=""></div></div></div>_______________________________________________<br class="">Pw_forum mailing list<br class=""><a href="mailto:Pw_forum@pwscf.org" class="">Pw_forum@pwscf.org</a><br class="">http://pwscf.org/mailman/listinfo/pw_forum</div></blockquote></div><br class=""></div></body></html>