<div dir="ltr">To the last point, for a solution the geometry optimization will not give you the global minimum.<br><br>On Saturday, November 30, 2013 12:14:56 PM UTC+1, Andreas Achazi wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><p class="MsoNormal"><span lang="EN-US">Dear all,</span></p>
<p class="MsoNormal"><span lang="EN-US">I would
like to determine the binding energy of a dimer in solution. </span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I simulated
the bound dimer and the unbound dimer surrounded by methanol with classical MD
in GROMACS. The system consists of 800 Atoms (C, N, O and H-Atoms).</span></p>
<p class="MsoNormal"><span lang="EN-US">Now would
like to calculated the bound state and the unbound state with cp2k ( with
BLYP-D3) and compare the energy.</span></p>
<p class="MsoNormal"><span lang="EN-US">But I don't
know how to get comparable energies.</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I would now
start to optimize cells with CELL_OPT (with DIRECT_CELL_OPT). Than optimize the
structure with GEO_OPT. </span></p>
<p class="MsoNormal"><span lang="EN-US">So my
questions are:</span></p>
<p class="MsoNormal"><span lang="EN-US">Is this the
best way or is there a other way to get the binding energy? </span></p>
<p class="MsoNormal"><span lang="EN-US">Is it
possible to calculated the binding energies in this way? </span></p>
<p class="MsoNormal"><span lang="EN-US">I fear that
the cells of bound and unbound state after the optimizations have not exactly
the identical dimensions. In addition, the starting structure (that I received
with GROMACS) leads possibly not to the global minimum.</span></p><p class="MsoNormal"><span lang="EN-US"><br></span></p><p class="MsoNormal"><span lang="EN-US">greetings </span></p><p class="MsoNormal"><span lang="EN-US">Andreas</span></p></div></blockquote></div>