<div>As a followup note, I had more errors in my first email, so please disregard the numbers except for the main question:</div><div><br /></div><div>The barostat mass I calculated with<br />N_f = 3*64 atoms</div><div>T = 1200 K</div><div>t_p = 50 fs</div><div><br /></div><div>is W = 1.3243919e-49 kg*m2. If I normalize it dividing by the Bohr radius squared, W = 4.7294895e-29 kg.</div><div><br /></div><div>Converted: W = 0.0284816321 amu or W = 51.9188808691 m_e, which is still nowhere close to the ~10^6 value that my RESTART file shows for the CP2K barostat mass. That is where I would love some suggestions. Thank you!</div><div><br /></div><div>Michela<br /></div><br /><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, August 27, 2024 at 12:18:25 PM UTC-4 Michela Benazzi wrote:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">* Degrees of freedom = 3*N atoms, and the units on my answer are J*s2 = kg*s2. <br>Sorry about the typos. Is the number normalized by the Bohr radius^2?<br><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, August 27, 2024 at 9:06:47 AM UTC-4 Michela Benazzi wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>Hello CP2K users,</div><div>I have previously asked a question about what kind of barostat CP2K uses, and Thomas Kuhne linked a paper on MTTK barostat which was very helpful (<a href="https://aiichironakano.github.io/phys516/Martyna-Integrator-MolPhys96.pdf" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://aiichironakano.github.io/phys516/Martyna-Integrator-MolPhys96.pdf&source=gmail&ust=1724863219282000&usg=AOvVaw1jHUI2zGrlMh8mN8LhGwpZ">https://aiichironakano.github.io/phys516/Martyna-Integrator-MolPhys96.pdf</a>).</div><div><br></div><div>However, I tried to calculate my barostat mass to understand the units and I am still at a loss - currently, my restart BAROSTAT MASS is 3.1175614526535734E+006. According to the CP2K manual, the units could be kg, m_e or amu. I tried to calculate it myself following the MTTK formula and there is no match:<br><br>W = (N_f + 9)* (k_b*T)/2 * (t_p/2pi)^2</div><div><br></div><div>where t_p is the time constant (50 fs), T = 1200 K and N_f is degrees of freedom (aka number of atoms? 64 in my system).</div><div><br></div><div>My result is 6.0124759e-47 J (kg*m2), which is in units of moment of inertia. Even if I convert it to m_e or amu it does not match:<br>
6.0124759e-47 J (kg*m2)
<p style="margin:0in;font-family:Calibri;font-size:11pt">(or 3.61328477e+27
amu*m2)</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt">(or
6.60031109024e-17 m_e*m2)</p><p style="margin:0in;font-family:Calibri;font-size:11pt"><br></p><p style="margin:0in;font-family:Calibri;font-size:11pt">I was wondering if:</p><p style="margin:0in;font-family:Calibri;font-size:11pt"><br></p><p style="margin:0in;font-family:Calibri;font-size:11pt">1) there are other units I have not considered in CP2K, or if CP2K internally converts to something else.</p><p style="margin:0in;font-family:Calibri;font-size:11pt">2) Degrees of freedom =/= number of atoms?</p><p style="margin:0in;font-family:Calibri;font-size:11pt">3) I am supposed to get rid of the m2 term by dividing by area in some way, although I am not sure how scientifically sound it would be, since we have a 3D unit cell.</p><p style="margin:0in;font-family:Calibri;font-size:11pt"><br></p><p style="margin:0in;font-family:Calibri;font-size:11pt">Thank you very much!<br></p>
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