Dear all,<br><br> I am doing test calculations for orthorhombic
layered compounds having van der waals forces. i calculated the volume
by varying c/a, b/a and a with energy and taken the minimum values of
c/a, b/a and a. But my volume change is surprisingly 2% with
experimental ( even van der waals forces having). I tried with the
"vc-relax" for same system i found 12% volume change with experimental.I
tried with psedopotentials also and the results are same. <br>
<br>I am very thankful any to solve this problem. <br><br>Thanks in advance<br><br>S.Appalakondaiah<br>Research Scholar<br>University of hyderabad<br>Hyderabad<br>India<br>