<html><head></head><body><div class="yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" data-setdir="false">Hello all,</div><div dir="ltr" data-setdir="false">i am working on 2 D sheet and i was confused about one thing that whether one should fix the z -coordinate doing relaxation(not vc-relaxation ) for calculation , and in which conditions do we fix the positions except for slab model</div></div></body></html>