<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1450695527382_7752">Good day everyone </div><div id="yui_3_16_0_1_1450695527382_7752">I need some help with clarification on celldm(4)=cos(ab) </div><div id="yui_3_16_0_1_1450695527382_7752"><br></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr">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">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"><br></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr">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"><br></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr">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"><br></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr">Am i getting the cos(ab) wrong</div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr"><br></div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr">Many Thanks to everyone on this forum </div><div id="yui_3_16_0_1_1450695527382_7752" dir="ltr"><br></div></div></body></html>