<div dir="ltr"><div>Hi</div><div><br></div><div>Please replace your &SCF section with the following settings, which should significantly accelerate your SCF calculations:</div><div><br></div><div> &SCF<br> MAX_SCF 20<br> EPS_SCF 1.000E-06<br> SCF_GUESS RESTART<br> &OT T<br> MINIMIZER DIIS<br> PRECONDITIONER FULL_ALL<br> ENERGY_GAP 0.001<br> &END OT<br> &OUTER_SCF T<br> EPS_SCF 1.000E-06<br> MAX_SCF 20<br> &END OUTER_SCF<br> &END SCF</div><div><br></div><div>You can use PBE pseudopotential for BEEF functional. It takes time to generate and test the performance of new basis sets and pseudopotentials. The PBE pseudopotential is perhaps the "closest" choice you have for BEEF functional, and it should be good enough for BEEF functional, but you need to test it.</div><div><br></div><div>In terms of choice of XC functional, please note BEEF functional contains parameters which were optimised for several data sets chosen by the original authors. There is no guarantee that it is good for your system. So you need to test the functional on your specific system. You may want to try PBE+D3 which I mentioned in the slides. Generally speaking, D2/D3 should be cheaper than non-local vdW based methods, but they may have their own advantages and disadvantages.</div><div><br></div><div>With respect to the supercell sizes, please keep in mind CP2K uses Gamma-point approximation. I am not sure whether you will be able to get correct electronic structure of your system if you use a 1x1x1 cell with cell dimensions smaller than 5 A. If the electronic structure is wrong, then the forces, stress tensor and optimised lattice parameters will also be wrong. You will be more likely to get better electronic structure if you use bigger supercells.</div><div><br></div><div>SL</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On 7 October 2015 at 19:34, Alex <span dir="ltr"><<a href="mailto:nedo...@gmail.com" target="_blank">nedo...@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Thanks Matt.<div><br></div><div>I enforced the angles and changed my SCF section to, hope this looks reasonable:</div><div><br></div><div><div> &SCF</div><div> &OT ON</div><div> MINIMIZER DIIS</div><div> PRECONDITIONER FULL_ALL</div><div> ENERGY_GAP 0.001</div><div> &END OT</div><span><div> SCF_GUESS RESTART </div><div> EPS_SCF 5.0E-6</div><div> MAX_SCF 300</div></span><div> &END SCF</div><div><br></div><div>Given the above, I do not see much of an improvement speed-wise, to be honest. The memory footprint is about half of what it was, I can see that much.</div><div><br></div><div>Your comment regarding XC is definitely well taken, we here don't believe PBE+VDW out of the box should be accurate. I am tempted to try the setup from p. 21 of the pdf you suggested, but does this BEEF work in stock CP2K and does one need to change the potentials (I am using GTH potentials). I suppose this boils down to whether there is an input file from the authors for others to try...</div><span class="HOEnZb"><font color="#888888"><div><br></div><div>Alex</div></font></span><div><div class="h5"><div><br></div><br>On Wednesday, October 7, 2015 at 2:37:42 AM UTC-6, Matt W wrote:<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div dir="ltr">Hi Alex,<div><br></div><div>one concern would be the XC functional. There are some slides from a recent CECAM meeting at <a href="http://www.cp2k.org/_media/events:2015_cecam_tutorial:ling_vdw.pdf" target="_blank" rel="nofollow">http://www.cp2k.org/_media/events:2015_cecam_tutorial:ling_vdw.pdf</a> with some partial inputs of setting up DFT-vdw functionals. I'm not sure PBE+vdw is great.</div><div><br></div><div>Otherwise, there are some things that might be a bit more efficient:</div><div><br></div><div>Changing to the OT method instead of using diagonalization would give you a very large speed up, I would think (order of magnitude probably here).</div><div><br></div><div>It might be a good idea to fix the angles of the cell and do an optimization (CELL_OPT/KEEP_ANGLES) then optimize again without the constraint.</div><div><br></div><div>Matt<br><br>On Tuesday, October 6, 2015 at 7:35:18 PM UTC+1, Alex wrote:<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid"><div dir="ltr">Hi all,<div><br></div><div>We're trying to simulate an n-octane crystal (triclinic, coordinates and cell vectors from literature) -- just a static cell + geometry optimization. Here's the issue: when simulating a single cell (1 1 1), the crystal cohesive energy is far above the experiment -- an order of magnitude larger in absolute value. As a vacuum ref we're simulating an isolated octane molecule. In all cases, a NON_LOCAL vdw energy correction is used.</div><div><br></div><div>When simulating a total of eight cells (2 2 2), and the simulation is still running, so the results are preliminary, things appear to be much more reasonable. The input file is below (I can provide the coordinates as well, if needed). Can you just by simple inspection tell me if anything is obviously wrong?</div><div><br></div><div>Thanks a lot,</div><div><br></div><div>Alex</div><div><br></div><div>**********************************</div><div><div>&GLOBAL</div><div> PROJECT opt</div><div> PRINT_LEVEL MEDIUM </div><div> RUN_TYPE CELL_OPT</div><div>&END GLOBAL</div><div> &MOTION</div><div> &GEO_OPT</div><div> OPTIMIZER BFGS </div><div> &END</div><div> &CELL_OPT</div><div> EXTERNAL_PRESSURE [bar] 1.0</div><div> OPTIMIZER BFGS</div><div> &END</div><div>&END MOTION</div><div> </div><div>&FORCE_EVAL</div><div> METHOD QS</div><div> STRESS_TENSOR ANALYTICAL</div><div> &DFT</div><div> BASIS_SET_FILE_NAME BASIS_SET2</div><div> POTENTIAL_FILE_NAME GTH_POTENTIALS2</div><div> &MGRID</div><div> NGRIDS 5</div><div> CUTOFF 500</div><div> &END MGRID</div><div> &QS</div><div> METHOD GPW</div><div> &END QS</div><div> &SCF</div><div> SCF_GUESS RESTART </div><div> EPS_SCF 5.0E-6</div><div> MAX_SCF 300</div><div> ADDED_MOS 100 </div><div> &MIXING</div><div> METHOD BROYDEN_MIXING</div><div> ALPHA 0.1</div><div> NBROYDEN 8</div><div> &END MIXING</div><div> &END SCF</div><div> &XC</div><div> &XC_FUNCTIONAL PBE</div><div> &END XC_FUNCTIONAL</div><div> &VDW_POTENTIAL NON_LOCAL</div><div> &END VDW_POTENTIAL</div><div> &END XC</div><div> &END DFT</div><div> &SUBSYS</div><div> &CELL</div><div> <span style="white-space:pre-wrap"> </span>ABC<span style="white-space:pre-wrap"> </span>4.160 4.750 11.000</div><div><span style="white-space:pre-wrap"> </span>ANGLES<span style="white-space:pre-wrap"> </span>94.80 84.50 105.10</div><div> PERIODIC XYZ</div><div><span style="white-space:pre-wrap"> </span>SYMMETRY TRICLINIC</div><div> MULTIPLE_UNIT_CELL 2 2 2 </div><div> &END</div><div> &TOPOLOGY</div><div> COORD_FILE_NAME noct_2mol.pdb</div><div> COORD_FILE_FORMAT PDB</div><div> MULTIPLE_UNIT_CELL 2 2 2 </div><div> &END</div><div> &KIND C</div><div> BASIS_SET DZVP-MOLOPT-SR-GTH</div><div> POTENTIAL GTH-PBE-q4</div><div> &END KIND</div><div> &KIND H</div><div> BASIS_SET DZVP-MOLOPT-SR-GTH</div><div> POTENTIAL GTH-PBE-q1</div><div> &END KIND</div><div>&END SUBSYS</div><div>&END</div><div><br></div></div></div></blockquote></div></div></blockquote></div></div></div></div><div class="HOEnZb"><div class="h5">
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