<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Finding the global minimum of a system may be difficult. Relaxation converge to the nearest local minimum. Chemical intuition may help to make good guesses but sometime it is not enough.<br><br>Simulated annealing would be a general purpose very expensive often overkilling never guaranteed approach </div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">Random sampling, Genetic or evolutionary algorithms are other approaches used </div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">stefano <div>(sent from my phone)</div></div><div><br>On 01 Jul 2016, at 17:13, ZARA NBSH <<a href="mailto:z.nrbsh@gmail.com">z.nrbsh@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_default" style="color:rgb(32,18,77)">Dear all,<br></div><div class="gmail_quote"><div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div style="color:rgb(32,18,77)">I would like to study the interaction between 2 organic molecules (contains O, H, and C atoms).</div><div style="color:rgb(32,18,77)">As the first step I relax<div style="color:rgb(32,18,77);display:inline">ed</div> the structure<div style="color:rgb(32,18,77);display:inline"></div> <div style="color:rgb(32,18,77);display:inline">(</div>using<div style="color:rgb(32,18,77);display:inline"> calculation = 'relax' in &control)</div><div style="color:rgb(32,18,77);display:inline">.</div></div><div style="color:rgb(32,18,77)"><div style="color:rgb(32,18,77);display:inline">M</div>y problem is that after finishing the run, it could not find the lowest energy s<div style="display:inline">tructure</div>.</div><div style="color:rgb(32,18,77)">And I could<div style="color:rgb(32,18,77);display:inline"> find some new structures (by hand) with</div> lower <div style="color:rgb(32,18,77);display:inline">energies</div>.</div><div style="color:rgb(32,18,77)">The <div style="color:rgb(32,18,77);display:inline">energy </div>difference<div style="color:rgb(32,18,77);display:inline">,</div><div style="color:rgb(32,18,77);display:inline"> ~</div>10<div style="color:rgb(32,18,77);display:inline">0</div> meV<div style="color:rgb(32,18,77);display:inline">,</div> is <div style="color:rgb(32,18,77);display:inline">strongly higher</div> than the accuracy of energy<div style="color:rgb(32,18,77);display:inline"> in my calculations; and also the structures are very different. </div></div><div style="color:rgb(32,18,77)"><div style="color:rgb(32,18,77);display:inline"><br></div></div><div style="color:rgb(32,18,77)"><div style="color:rgb(32,18,77);display:inline">In my calculation, the</div> vacuum<div style="color:rgb(32,18,77);display:inline"> is large enough and forc_conv_thr is 1.0D-5.</div></div><div style="color:rgb(32,18,77)"><br></div><div style="color:rgb(32,18,77)">My question is how can I find the lowest energy <div style="color:rgb(32,18,77);display:inline">structure</div>?</div><div style="color:rgb(32,18,77)"><br></div><div style="color:rgb(32,18,77)">Bests,</div><div style="color:rgb(32,18,77)"><div class="gmail_default" style="color:rgb(32,18,77)">zara</div><div class="gmail_default" style="color:rgb(32,18,77)"></div><br></div></div></div></div></div></div>
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