<div dir="ltr"><div><p class="MsoNormal">Hi, to make things easier in demonstrating what Claudio is
describing I put a Li atom in a box and requested that its initial temperature
be 1200K. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">CP2k writes:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"># Step Nr. Time[fs] Kin.[a.u.] Temp[K] Pot.[a.u.] Cons Qty[a.u.] UsedTime[s]<o:p></o:p></p>
<p class="MsoNormal"> 0 0.000000 <b><u>0.005700268 </u></b> 1200.000000000 0.000000000 0.011400535 0.000000000<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The velocity reported for that single atoms is:<o:p></o:p></p>
<p class="MsoNormal"> 1<o:p></o:p></p>
<p class="MsoNormal"> i = 0, time = 0.000, E = 0.0000000000<o:p></o:p></p>
<p class="MsoNormal"> Li <b>0.0000000000 0.0000000000 0.0009492302</b><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For that single atom we have:<o:p></o:p></p><p class="MsoNormal"><br></p>
<p class="MsoNormal">0.5*m*v^2=0.5*6.914*0.0009492302^2=<b>0.00000312705</b> This is in CP2K's atomic units.</p><p class="MsoNormal"><br></p><p class="MsoNormal"><br></p><p class="MsoNormal">Now if I follow the manual’s instruction “Having an atom
with a mass m in AMU the kinetic energy 1/2mv^2 will be obtained in Hartree
(i.e. au) multiplying by 911.447”<br></p><p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal">I get:<o:p></o:p></p><p class="MsoNormal"><br></p>
<p class="MsoNormal">0.00000312705*911.447=<b>0.00285014242</b> </p><p class="MsoNormal"> </p>
<p class="MsoNormal">which is exactly half of the kinetic energy reported by
CP2K.<o:p></o:p></p>
<p class="MsoNormal"><br></p><p class="MsoNormal">[0.005700268 / 2] see beginning of this same post.<o:p></o:p></p><div><br></div><p class="MsoNormal">Could someone kindly clarify how this is possible/correct?</p><p class="MsoNormal">Also, the reported temperature matches the reported kinetic energy but obviously not what one would
derive from the velocity.<br></p><p class="MsoNormal"><o:p></o:p></p></div><div><br></div><div>Thank you,</div><div><br></div><div>Fei</div><div><br></div><div><br></div><div><br></div><div>On Tuesday, June 18, 2019 at 7:50:04 PM UTC-5, Claudio wrote:<br></div><blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">Dear all, </div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">first <span title="Search for suggestions" style="font:inherit;vertical-align:baseline;color:inherit">thanks in advance</span> for your help.</div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">I have a very simple question (perhaps a units misunderstanding on my part). I am simulating classically in the NVT ensemble a simple AB type molten salt with a polarizable potential. <span style="font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;vertical-align:baseline">When I write out the velocities along my simulation and I try to compute the kinetic energy using these via the expression:</span></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">1/2 Sum_i { m_i v_i dot v_i} and multiply by the conversion factor 911.447 --as per the manual-- </div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">"Having an atom with a mass m in AMU the kinetic energy 1/2mv^2 will be obtained in Hartree (i.e. au) multiplying by 911.447"</div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">I get a number in Hartrees that is exactly 1/2 of that printed out by CP2K each frame. I can't seem to understand how to reconcile these two numbers. Is there something I am overlooking?</div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">Thanks once again for your kind help and consideration. I can provide the velocities of a snapshot and a simple code to compute the kinetic energy if needed, but this is so simple that I doubt the problem is in the code.</div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">Best regards</div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:"Palatino Linotype","Book Antiqua",Palatino,serif;vertical-align:baseline;color:rgb(0,0,0)">Claudio</div></div></blockquote></div>