<div dir="ltr">Hi Ali,<div><br></div><div>Thanks for the response! I am using 400 Ry because I needed it to be the same cutoff that I used in some other AIMD simulations in the condensed phase. Regardless, I have tried the suggested changes and I still get imaginary frequencies. I am quite surprised that cp2k is having a hard time with such simple small systems, am I missing something?</div><div><br></div><div>Best,</div><div>Luis</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jan 25, 2017 at 9:35 AM, Ali KACHMAR <span dir="ltr"><<a href="mailto:ali.kac...@gmail.com" target="_blank">ali.kac...@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear Luis,<div> <br></div><div>1. a cutoff of 400 Ry is a bit low for geometry optimization + vibrational frequency calculations on water systems. Please run your geometry optimization with tight convergence and a cutoff=550 Ry, Relcutoff=70 Ry</div><div><br></div><div>2. Starting from the optimized geometry, please run your vibrational analysis calculation using a DX=0.01, and add to the GEO_OPT section </div><div><br></div><div><div> &GEO_OPT</div><div> TYPE MINIMIZATION</div><div> OPTIMIZER CG</div><div> &END GEO_OPT</div><div><br></div></div><div><br></div><div>All the best,</div><div>Ali</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote"><span class="">On Tue, Jan 24, 2017 at 6:00 PM, <span dir="ltr"><<a href="mailto:lar...@lbl.gov" target="_blank">lar...@lbl.gov</a>></span> wrote:<br></span><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><div dir="ltr">I am trying to compute the vibrational frequencies of small water clusters, and I am having trouble getting rid of imaginary frequencies, even for the water dimer, using very tight convergence parameters during the geometry optimization.I have also tried to run the simulations with periodic boundary conditions, different values of the displacement, etc., but I still get a few imaginary frequencies. I have run out of ideas to try so any advice will be greatly appreciated. I have attached here the input files of the calculations. <div><br></div><div>Thanks for your time!</div><div>Luis</div></div></span><span class="m_8271249234666261054HOEnZb"><font color="#888888"><span class="HOEnZb"><font color="#888888">
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><span style="color:rgb(136,136,136);font-size:12.8000001907349px">Luis A. Ruiz Pestana, PhD</span><div style="color:rgb(136,136,136);font-size:12.8000001907349px">Postdoctoral Fellow</div><div style="color:rgb(136,136,136);font-size:12.8000001907349px">University of California, Berkeley</div><div style="color:rgb(136,136,136);font-size:12.8000001907349px">Lawrence Berkeley National Laboratory</div><div style="color:rgb(136,136,136);font-size:12.8000001907349px">Berkeley, CA 94720</div></div></div></div></div></div></div></div>
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