<div dir="ltr">Great. The manual is a wiki, you can edit it as you suggest. You should edit the development version, though:<div><br></div><div><a href="https://manual.cp2k.org/trunk/CP2K_INPUT/MOTION/PRINT/VELOCITIES.html">https://manual.cp2k.org/trunk/CP2K_INPUT/MOTION/PRINT/VELOCITIES.html</a><br><br>On Wednesday, June 19, 2019 at 8:52:53 PM UTC+1, fei wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><div><p class="MsoNormal">This is in the &MOTION &PRINT &VELOCITIES
section of the input file.</p>
<p class="MsoNormal"><br></p><p class="MsoNormal">See:</p>
<p class="MsoNormal"><a href="https://manual.cp2k.org/cp2k-6_1-branch/CP2K_INPUT/MOTION/PRINT/VELOCITIES.html#UNIT" target="_blank" rel="nofollow" onmousedown="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fmanual.cp2k.org%2Fcp2k-6_1-branch%2FCP2K_INPUT%2FMOTION%2FPRINT%2FVELOCITIES.html%23UNIT\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNE2ErW-9TSFQ1NF6L7wk6-1NcpzDg';return true;" onclick="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fmanual.cp2k.org%2Fcp2k-6_1-branch%2FCP2K_INPUT%2FMOTION%2FPRINT%2FVELOCITIES.html%23UNIT\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNE2ErW-9TSFQ1NF6L7wk6-1NcpzDg';return true;">https://manual.cp2k.org/cp2k-<wbr>6_1-branch/CP2K_INPUT/MOTION/<wbr>PRINT/VELOCITIES.html#UNIT</a></p>
<p class="MsoNormal"><br></p><p class="MsoNormal">“Section VELOCITIES</p>
<p class="MsoNormal">Controls the output of the velocities. The default unit for
velocities is bohr/au_time. The au_time is derived from the hbar value
(1.054e-34 J*sec) and the value of the hartree unit of energy (27.21 eV or
4.359e-18 J) as hbar/Ehartree = 2.42e-17 sec = 0.0242 fs. 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 .</p>
<p class="MsoNormal">Section path: CP2K_INPUT / MOTION / PRINT / VELOCITIES”</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">To be clear, we think that the velocities and kinetic energy
are correct, but the manual is wrong or at least misleading in the conversion between these. </p><p class="MsoNormal"><br></p><p class="MsoNormal"><br></p>
<p class="MsoNormal">This is the argument:</p>
<p class="MsoNormal">Assume that you have an atom with a mass of 1 AMU and velocity
of 1 in bohr/au_time then the kinetic energy is:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">1/2 *1 AMU *(1 bohr/au_time)^2 = 911.447 Hartree</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Instead, an atom with mass “M” in AMU and velocity “v” in bohr/au_time
will have a kinetic energy of</p><p class="MsoNormal"><br></p>
<p class="MsoNormal">911.447 * M *v^2 in Hartree</p>
<p class="MsoNormal"><br></p><p class="MsoNormal">Hence, the conversion factor between Ke=1/2 M v^2 with M in
AMU and v in bohr/au_time is not 911.447
as we read from the manual but instead (911.447 * 2).</p><p class="MsoNormal"><br></p><p class="MsoNormal"><br></p>
<p class="MsoNormal"><b>We believe the manual should say: “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 1822.894”</b></p></div><div><br></div><div><br></div><div><br></div><div><br></div>On Wednesday, June 19, 2019 at 12:34:29 PM UTC-5, Matt W wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hello,</div><div><br></div>where in the manual are you referring to?<div><br></div><div>Matt<br><br>On Wednesday, June 19, 2019 at 6:17:06 PM UTC+1, fei wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><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. </p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">CP2k writes:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"># Step Nr. Time[fs] Kin.[a.u.] Temp[K] Pot.[a.u.] Cons Qty[a.u.] UsedTime[s]</p>
<p class="MsoNormal"> 0 0.000000 <b><u>0.005700268 </u></b> 1200.000000000 0.000000000 0.011400535 0.000000000</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">The velocity reported for that single atoms is:</p>
<p class="MsoNormal"> 1</p>
<p class="MsoNormal"> i = 0, time = 0.000, E = 0.0000000000</p>
<p class="MsoNormal"> Li <b>0.0000000000 0.0000000000 0.0009492302</b></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">For that single atom we have:</p><p class="MsoNormal"><br></p>
<p class="MsoNormal">0.5*m*v^2=0.5*6.914*0.<wbr>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"></p>
<p class="MsoNormal">I get:</p><p class="MsoNormal"><br></p>
<p class="MsoNormal">0.00000312705*911.447=<b>0.<wbr>00285014242</b> </p><p class="MsoNormal"> </p>
<p class="MsoNormal">which is exactly half of the kinetic energy reported by
CP2K.</p>
<p class="MsoNormal"><br></p><p class="MsoNormal">[0.005700268 / 2] see beginning of this same post.</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"></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></blockquote></div></div></blockquote></div></blockquote></div></div>