<p dir="auto">I used the driver/optimizer couple GO/rational for DFTB+ and explored a few SCC
epsilon parameters (expressed below as 1e-n). For CP2K with BFGS optimizer, I similarly explored various values for SCF
epsilon. Epsilons for geometry of 1e-5 or 1e-6 yields very similar results.<br></p>
<p dir="auto">CP2K (all other epsilons are default):<br>
n Volume(A3)<br>
5 1870.51<br>
6 1863.46<br>
7 1873.30<br>
8 1759.92<br>
9 1834.73<br>
10 1944.21<br>
11 1761.18<br>
12 1846.56<br>
13 1860.54<br>
14 1826.25<br>
15 1852.36</p>
<p dir="auto">The differences are large, and non-monotonic. There is,
imo, no obvious choice. I also quickly checked that without constraining
the monoclinic geometry, it was actually preserved.</p>
<p dir="auto">DFTB+:<br>
5 1901.99<br>
6 1859.22<br>
7 1904.44<br>
8 1902.72<br>
9 1900.05<br>
10 1900.89<br>
11 1901.01<br>
12 1900.90<br>
13 1900.35</p>
<p dir="auto">Note that the only one preserving the monoclinic geometry
is 1e-6. For
all the other epsilons, Alpha and Gamma are around 90.2° and 90.7°, respectively, instead of 90°. But all those other volumes are very similar. Would it mean we
have to avoid 1e-6 for DFTB+? Or the contrary?</p>
<p dir="auto">Any remarks that could help?<br></p><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Thursday, April 7, 2022 at 5:05:34 PM UTC-5 Xavier Bidault 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,</div><div><br></div><div>I just posted also on DFTB+ issues (<a href="https://github.com/dftbplus/dftbplus/issues/1001" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://github.com/dftbplus/dftbplus/issues/1001&source=gmail&ust=1649730476269000&usg=AOvVaw1mRa2nyrc6E_JDahBbJ1La">https://github.com/dftbplus/dftbplus/issues/1001</a>), including the input script for DFTB+</div><div><br></div><div>Xavier<br></div><br><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, April 5, 2022 at 3:22:02 PM UTC-5 Xavier Bidault 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,</div><div><br></div><div>I run a variable-cell optimization of a high-energy molecular crystal, beta-HMX, with CP2K 9.1 and DFTB+ 21.2, both using GFN1-xTB, which includes D3(BJ) correction. To compare apples to apples, I optimized the same supercell, using the Gamma point. The initial (experimental) volume for the supercell is 2069.80 A3. The resulting volume is:</div><div>1950.83 A3 with DFTB+</div><div>1759.92 A3 with CP2K</div><div><br></div><div>In order to check if I did something wrong in the configuration files, I used DFTB + D3(0) with the default DFTB parameter file from CP2K for both CP2K and DFTB+, and I find:</div><div>1467.79 A3 with DFTB+<br></div><div>1467.14 A3 with CP2K</div><div>So, DFTB + D3(0) is consistent between CP2K and DFTB+, but not GFN1-xTB.<br></div><div><br></div><div>IMO, the dispersion correction of xTB is wrong somewhere in CP2K. Looking at the difference between CP2K and DFTB+, could it be that D3(BJ) correction is counted twice in CP2K? Or with some wrong units we don't have access to?</div><div><br></div><div>I attached the CP2K input file for the GFN1-xTB calculation.</div><div><br></div><div>Please, let me know.</div><div><br></div><div>Thank you,</div><div>Xavier<br></div><div><br></div><div><br></div></blockquote></div></blockquote></div>
<p></p>
-- <br />
You received this message because you are subscribed to the Google Groups "cp2k" group.<br />
To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>.<br />
To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/96beee3f-c95d-4bf5-a2da-2dbe9a3a210cn%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/96beee3f-c95d-4bf5-a2da-2dbe9a3a210cn%40googlegroups.com</a>.<br />