Hi Matthias,<div><br /></div><div>Thanks for clarifying this for me. It was indeed a bit confusing, but I'm happy that I have a clear answer now!</div><div><br /></div><div>Kind regards,</div><div>Léon<br /><br /></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Friday 12 January 2024 at 11:08:26 UTC+1 Krack Matthias 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;">
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Hi Léon<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Yes, 110 kcalmol*rad^-2 and 900 kcal*Angstrom^-2 are correct. Note, that the inputs in cp2k/tests are for code regression testing and the parameters used therein are
not reliable by contrast to the example inputs given in the exercises. Unfortunately, many regression tests use this incorrect flexible TIP3P force field. This is most likely a copy-paste error which is indeed confusing for users. I will fix that.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Best
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Matthias<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p>
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<b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">From:
</span></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of Léon Luntadila Lufungula <<a href data-email-masked rel="nofollow">Leon.luntad...@uantwerpen.be</a>><br>
<b>Date: </b>Friday, 12 January 2024 at 10:09<br>
<b>To: </b>cp2k <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>><br>
<b>Subject: </b>Re: [CP2K:19729] Correct TIP3P parameters<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Hi Alin and Matthias,<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Thanks for the quick reply, I didn't know that! If so, the 110/900 combination in the water.inp file should be correct then right? Still, in a lot of input files in the tests folder
like for example cp2k/tests/Fist/regtest-4/H2O-1.inp (see attachment) the combination 55/450 is used. Can you explain why this is the case then?<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Kind regards,<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Léon<u></u><u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p>
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<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">On Friday 12 January 2024 at 10:02:01 UTC+1 Krack Matthias wrote:<u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt">Dear Léon</span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt"> </span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt">Note that LAMMPS uses a d</span><a href="https://docs.lammps.org/angle_harmonic.html" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://docs.lammps.org/angle_harmonic.html&source=gmail&ust=1705142215987000&usg=AOvVaw1R99KmNN6PbaM4Qu9A9fzf"><span lang="EN-US" style="font-size:11.0pt">ifferent potential definition</span></a><span lang="EN-US" style="font-size:11.0pt">.
By contrast to CP2K, LAMMPS includes the prefactor ½ into the constant K.</span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt"> </span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt">HTH</span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt"> </span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt">Matthias </span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span lang="EN-US" style="font-size:11.0pt"> </span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">From:
</span></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><span><a href data-email-masked rel="nofollow">cp...@googlegroups.com</a></span> <<span><a href data-email-masked rel="nofollow">cp...@googlegroups.com</a></span>> on behalf of Léon Luntadila Lufungula <<span><a href data-email-masked rel="nofollow">Leon.luntad...@uantwerpen.be</a></span>><br>
<b>Date: </b>Friday, 12 January 2024 at 09:53<br>
<b>To: </b>cp2k <<span><a href data-email-masked rel="nofollow">cp...@googlegroups.com</a></span>><br>
<b>Subject: </b>[CP2K:19726] Correct TIP3P parameters</span><span style="font-size:11.0pt"><u></u><u></u></span></p>
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<span style="font-size:11.0pt">Dear all,<u></u><u></u></span></p>
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<span style="font-size:11.0pt"> <u></u><u></u></span></p>
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<span style="font-size:11.0pt">Just a quick question about the parameters for the TIP3P forcefield. In the example files (see attached water.inp) of the
</span><a href="https://www.cp2k.org/exercises:2019_uzh_acpc2:ex02" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://www.cp2k.org/exercises:2019_uzh_acpc2:ex02&source=gmail&ust=1705142215987000&usg=AOvVaw1Y83cYd2a1SI0c3YsQ_i3g"><span style="font-size:11.0pt">exercise</span></a><span style="font-size:11.0pt"> on molecular simulation of water the TIP3P model is used to simulate water. In the input file,
I noticed that the force constant of the H-O-H bend and the H-O bond are 110 rad^-2kcalmol and 900 angstrom^-2kcalmol, respectively. However, when looking online for the parameters like on the
</span><a href="https://docs.lammps.org/Howto_tip3p.html" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://docs.lammps.org/Howto_tip3p.html&source=gmail&ust=1705142215987000&usg=AOvVaw1yZrS1CxAG2zQDNPYhywL-"><span style="font-size:11.0pt">lammps documentation</span></a><span style="font-size:11.0pt">, I find that these values are actually half of what is defined in the input, i.e., 55 rad^-2kcalmol
and 450 angstrom^-2kcalmol, respectively... Is this indeed an error in the input file or am I missing something here? Most water input files I see in the tests/Fist folder also contain the smaller values for the force constants.<u></u><u></u></span></p>
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<span style="font-size:11.0pt"> <u></u><u></u></span></p>
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<span style="font-size:11.0pt">Kind regards,<u></u><u></u></span></p>
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<span style="font-size:11.0pt">Léon<u></u><u></u></span></p>
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