<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:14pt"><div><span>Dear all</span></div><div><span><br></span></div><div><span>I try to get the optimized lattice parameters a and c of hexagonal structure with space group 161 R3c using both of the volume and c/a optimizations. My obtained results are not comparable (too great) to the experimental and theoretical data. </span></div><div><span>Can you show me the procedure of optimization with relaxation, please?</span></div><div><span><br></span></div><div> </div><div><font style="color:rgb(0, 0, 191);" size="4"><span style="font-style:italic;">Souheyla </span></font><br><br><br></div></div></body></html>