<div dir="ltr"><div>Hi,</div><div><br></div><div>Gas phase calculations are pretty simple to setup,</div><div><br></div><div><div style="background-color:rgb(250,250,250);border-color:rgb(187,187,187);border-style:solid;border-width:1px"><code><div><span style="color:#000"> </span><span style="color:#660">&</span><span style="color:#000">DFT<br><br>  </span><span style="color:#660">...</span><span style="color:#000"><br><br></span><b><span style="color:#000">  </span><span style="color:#660">&</span><span style="color:#000">POISSON<br>   POISSON_SOLVER  WAVELET<br>   PERIODIC  NONE<br>  </span><span style="color:#660">&</span><span style="color:#008">END</span><span style="color:#000"> POISSON</span></b><span style="color:#000"><br> </span><span style="color:#660">&</span><span style="color:#008">END</span><span style="color:#000"> DFT<br><br> </span><span style="color:#660">&</span><span style="color:#000">SUBSYS<br>  </span><span style="color:#660">&</span><span style="color:#000">CELL<br></span><b><span style="color:#000">   ABC   </span></b><b><span style="color:#066">30</span><span style="color:#000">  </span><span style="color:#066">30</span><span style="color:#000">  </span><span style="color:#066">30</span></b><span style="color:#000"><br>   ALPHA_BETA_GAMMA   </span><span style="color:#066">90</span><span style="color:#000">  </span><span style="color:#066">90</span><span style="color:#000">  </span><span style="color:#066">90</span><span style="color:#000"><br></span><b><span style="color:#000">   PERIODIC  NONE</span></b><span style="color:#000"><br>  </span><span style="color:#660">&</span><span style="color:#008">END</span><span style="color:#000"> CELL<br><br></span><span style="color:#660">...</span><span style="color:#000"><br><br>  </span><span style="color:#660">&</span><span style="color:#000">TOPOLOGY<br>   COORD_FILE_FORMAT XYZ<br>   COORD_FILE_NAME foo</span><span style="color:#660">.</span><span style="color:#000">xyz<br>   CONN_FILE_FORMAT off<br></span><b><span style="color:#000">   </span><span style="color:#660">&</span><span style="color:#000">CENTER_COORDINATES<br>   </span><span style="color:#660">&</span><span style="color:#008">END</span><span style="color:#000"> CENTER_COORDINATES</span></b><span style="color:#000"><br>  </span><span style="color:#660">&</span><span style="color:#008">END</span><span style="color:#000"> TOPOLOGY<br></span></div></code></div><br>Important bits in bold. You need to turn off PBC, use an appropriate Poisson solver, and then adjust the box size so that the electron density at the box edges will be close to 0 (usually about 10 Angstroms away from your molecule(s)). Center the coordinates as in the &TOPOLOGY section. That's it!<br></div><div><br></div><div>-T<br></div><div><br></div><div><br></div><br>On Monday, November 4, 2019 at 12:00:11 PM UTC-4, MD Simulation wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hello,<div><br></div><div>I would like to run a calculation without PBC, are there any examples?</div><div><br></div><div>Thanks!</div></div></blockquote></div>