<div dir="ltr"><div><div><div><div><div><div>Dear <span name="MR.Chem" class="">MR.Chem,<br><br></span></div><span name="MR.Chem" class=""> A few issues catching my attention:<br><br></span></div><div><span name="MR.Chem" class=""> - When you say "your results are always larger than the experimental data", I presume that you mean the binding energy of the CO molecule, right? You should not look at the experimental number but compare to best theoretical DFT-GGA (+ dispersion correction, if available)<br>
<br></span></div><div><span name="MR.Chem" class=""> - Gamma point might not be enough in your case (One could study the magnitude of this by performing calculations with other DFT code and increase the k point sampling)<br>
<br></span></div><div><span name="MR.Chem" class=""> - There is the problem with the basis set superposition error with Gaussian basis sets. Did you try to do the counterpoise correction to your energies?<br></span></div>
<div><span name="MR.Chem" class=""><br></span></div><span name="MR.Chem" class=""> - LSD is not really needed in these systems (at least back then when I studied exactly these systems for my PhD thesis), but shouldn't harm either - only a factor of two in CPU time and memory<br>
<br></span></div><span name="MR.Chem" class=""> - FORCE_EVAL / DFT / QS / EPS_DEFAULT 1e-10 is quite large, I would go for 1e-14 or so for the production runs<br><br></span></div><span name="MR.Chem" class=""> - I don't have any idea of the EPS_GVG and EPS_PGF_ORB - do you have a reason to expect that the default values were insufficient or did you optimise these values?<br>
<br></span></div><span name="MR.Chem" class=""> - The broadening of 3000 K is very large: A typical value in the literature is rather 600 or 1200 K (0.05 or 0.1 eV); well, one should actually perform the extrapolation to zero temperature in the total energies, but let us first assume that this would be similar both in the calculation of the slab with and without the molecule and thus would cancel quite well when calculating the binding energy<br>
<br></span></div><span name="MR.Chem" class=""> - You use revPBE as the exchange-correlation functional but specify 'REFERENCE_FUNCTIONAL PBE' - why this? In addition you specify the 'SCALING' as well: First of all we usually use a value of 1.0 (where did you get 1.25?? Pure PBE should have a value smaller than one if I remember correctly), and 'REFERENCE_FUNCTIONAL' and 'SCALING' are used for the same thing, to specify the s6 coefficient in the DFT-D2 scheme. Please only insert one of these keywords<br>
</span><div class="gmail_extra"><br></div><div class="gmail_extra"> - Which lattice constant do you use, did you optimise it yourself or did you use the experimental value?<br><br></div><div class="gmail_extra"> - Last but maybe not least, DFT-D2 is known to overestimate binding energies at transition metal surfaces<br>
</div><div class="gmail_extra"><br><br></div><div class="gmail_extra"> Here were a couple of suggestions to start with - good luck! :)<br><br></div><div class="gmail_extra"> Greetings,<br><br></div><div class="gmail_extra">
apsi<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/3/17 MR.Chem <span dir="ltr"><<a href="mailto:chemc...@gmail.com" target="_blank">chemc...@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear all,<div><br></div><div> I am studying the CO adsorbed on the metal surface, like Cu, Pd, Rh... However, my results are always larger than the experimental data, around 0.6eV. Does anyone have any experience about it?</div>
<div> Here is my code, can some expert help me to check it? Maybe something wrong with my code. </div><div>=================================================================================</div><div><div>&FORCE_EVAL</div>
<div> METHOD Quickstep</div><div> &DFT</div><div> CHARGE 0</div><div> LSD</div><div> POTENTIAL_FILE_NAME ../Basis_Set/GTH_POTENTIALS</div><div> BASIS_SET_FILE_NAME ../Basis_Set/BASIS_MOLOPT</div><div>
&MGRID</div><div> CUTOFF 500</div><div> NGRIDS 7</div><div> # REL_CUTOFF 40</div><div> &END MGRID</div><div> &QS</div><div> EPS_DEFAULT 1.0E-10</div><div> EPS_GVG 1.0E-8</div><div>
EPS_PGF_ORB 1.0E-8</div><div> EXTRAPOLATION PS</div><div> EXTRAPOLATION_ORDER 4 # find the best for your system</div><div> &DISTRIBUTION</div><div> SKIP_OPTIMIZATION TRUE</div><div> &END DISTRIBUTION</div>
<div> &END QS</div><div> &SCF</div><div> EPS_SCF 1.0E-8</div><div> MAX_SCF 200</div><div> EPS_SCF_HIST 1.0E-8</div><div> ADDED_MOS 500</div><div> CHOLESKY INVERSE </div><div> &SMEAR ON </div>
<div> METHOD FERMI_DIRAC </div><div> ELECTRONIC_TEMPERATURE [K] 3000</div><div> &END SMEAR </div><div> &DIAGONALIZATION </div><div> ALGORITHM STANDARD </div><div> &END DIAGONALIZATION </div>
<div> &MIXING </div><div> METHOD BROYDEN_MIXING </div><div> ALPHA 0.1 </div><div> BETA 1.5 </div><div> NBROYDEN 8 </div><div> &END</div><div> &OUTER_SCF</div>
<div> EPS_SCF 1.0E-8</div><div> MAX_SCF 100</div><div> STEP_SIZE 0.1</div><div> EXTRAPOLATION_ORDER 4</div><div> &END OUTER_SCF</div><div> &END SCF</div><div><br></div><div>
&XC</div><div> &XC_FUNCTIONAL PBE </div><div> &PBE</div><div> PARAMETRIZATION REVPBE</div><div> &END PBE</div><div> &END XC_FUNCTIONAL</div><div> &XC_GRID</div>
<div> XC_SMOOTH_RHO NN10</div><div> XC_DERIV SPLINE2_SMOOTH</div><div> &END XC_GRID</div><div> &vdW_POTENTIAL</div><div> DISPERSION_FUNCTIONAL PAIR_POTENTIAL</div><div> &PAIR_POTENTIAL</div>
<div> TYPE DFTD2</div><div> SCALING 1.25</div><div> REFERENCE_FUNCTIONAL PBE</div><div> R_CUTOFF 15.</div><div> &END PAIR_POTENTIAL</div><div> &END vdW_POTENTIAL</div>
<div> &END XC</div><div> &END DFT</div><div> &SUBSYS</div><div> &CELL</div><div> A 11.50460000 0.00000000 0.00000000</div><div> B -5.50230000 9.93026316 0.00000000</div>
<div> C 0.00000000 0.00000000 18.73890000</div><div> PERIODIC XYZ</div><div> &END CELL</div><div> &COORD</div><div> Pd 0.48065840 7.03842411 2.78730528</div><div>
Pd 0.47028763 0.44875232 7.19243429</div><div> Pd 4.53327500 2.99486842 0.48000000</div><div> Pd -0.92756268 6.26067797 4.99255153</div><div> Pd 7.28442500 2.99486842 0.48000000</div>
<div> Pd 1.95832508 6.23995572 4.98929589</div><div> Pd 5.90885000 5.37743421 0.48000000</div><div> Pd 0.59872433 8.73424560 4.94485704</div><div> Pd -2.34460000 5.37743421 0.48000000</div>
<div> Pd 3.48202628 8.75574050 4.90377153</div><div> Pd 7.60058003 4.66725820 2.69914002</div><div> Pd 2.12951115 7.91373487 7.19590876</div><div> Pd -0.98640158 4.60804088 2.78207535</div>
<div> Pd 4.99805700 7.90489627 7.18006023</div><div> Pd -2.37121774 7.06798024 2.77804336</div><div> Pd 9.11351163 0.44812200 7.18150630</div><div> Pd 3.15770000 5.37743421 0.48000000</div>
<div> Pd -2.28848592 8.75288986 4.94848842</div><div> Pd 1.86796693 4.57784447 2.79012924</div><div> Pd -3.64617921 7.90460435 7.19218894</div><div> Pd 4.71963320 4.58012708 2.78282947</div>
<div> Pd -0.75815898 7.91750314 7.22011766</div><div> Pd 3.32828364 7.03761292 2.77891925</div><div> Pd 3.35784019 0.45975453 7.21713253</div><div> Pd 6.20941143 7.12736713 2.68973994</div>
<div> Pd 6.24673072 0.45867465 7.19321178</div><div> Pd -0.96902500 2.99486842 0.48000000</div><div> Pd 4.84897874 6.26179049 4.94562009</div><div> Pd 1.78212500 2.99486842 0.48000000</div>
<div> Pd 7.67975198 6.28516301 4.93895128</div><div> Pd 0.40655000 5.37743421 0.48000000</div><div> Pd 6.31889141 8.77579565 4.89678117</div><div> Pd 5.90885000 0.61230263 0.48000000</div>
<div> Pd 0.45589201 3.77441599 4.98640728</div><div> Pd -0.88579308 9.52461840 2.71360432</div><div> Pd -0.91478538 2.92497807 7.20923011</div><div> Pd 1.96179550 9.52218444 2.70458723</div>
<div> Pd 1.97006436 2.93242210 7.23312886</div><div> Pd 6.11012640 2.11464388 2.77204082</div><div> Pd 0.59930677 5.42011629 7.25046349</div><div> Pd 8.99428358 2.20331457 2.69500697</div>
<div> Pd 3.49212409 5.42106046 7.22291798</div><div> Pd -3.72017500 7.76000000 0.48000000</div><div> Pd 7.61529378 1.28270688 4.91196377</div><div> Pd -0.96902500 7.76000000 0.48000000</div>
<div> Pd 10.44730149 1.30931768 4.91246466</div><div> Pd 3.15770000 0.61230263 0.48000000</div><div> Pd 9.06475984 3.80294084 4.93990249</div><div> Pd 3.25324319 2.10925105 2.78044950</div>
<div> Pd -2.28679605 5.41093586 7.22290884</div><div> Pd 1.78212500 7.76000000 0.48000000</div><div> Pd 1.83892428 1.28295401 4.95856743</div><div> Pd 4.53327500 7.76000000 0.48000000</div>
<div> Pd 4.72711559 1.26487439 4.95221711</div><div> Pd 8.66000000 0.61230263 0.48000000</div><div> Pd 3.34270002 3.75714799 4.98323499</div><div> Pd 0.40655000 0.61230263 0.48000000</div>
<div> Pd 6.23251524 3.77764121 4.94405153</div><div> Pd 4.84358673 9.61900376 2.62576793</div><div> Pd 4.86285578 2.93105916 7.20861165</div><div> Pd -3.73917975 9.55256951 2.70716721</div>
<div> Pd 7.72991049 2.91981062 7.19559113</div><div> Pd 0.39747135 2.13690410 2.77102245</div><div> Pd 6.35957458 5.40832411 7.20891859</div><div> C 2.04578180 6.20000000 9.00000000</div>
<div> O 2.04578180 6.66763600 10.20000000</div><div> &END COORD</div><div> &KIND Pd</div><div> BASIS_SET DZVP-MOLOPT-SR-GTH</div><div> POTENTIAL GTH-PBE-q18</div><div> &END KIND</div>
<div> &KIND O</div><div> BASIS_SET DZVP-MOLOPT-SR-GTH</div><div> POTENTIAL GTH-PBE-q6</div><div> &END KIND</div><div> &KIND C</div><div> BASIS_SET DZVP-MOLOPT-SR-GTH</div><div> POTENTIAL GTH-PBE-q4</div>
<div> &END KIND</div><div> &END SUBSYS</div><div>&END FORCE_EVAL</div><div><br></div><div>&GLOBAL</div><div> PROJECT Pd-CO-111surface-hcp</div><div> RUN_TYPE GEO_OPT</div><div> PRINT_LEVEL low</div>
<div>&END GLOBAL</div><div><br></div><div>&MOTION</div><div> &GEO_OPT</div><div> MAX_ITER 1000</div><div> OPTIMIZER BFGS</div><div> TYPE MINIMIZATION # TRANSITION_STATE</div><div> &END GEO_OPT</div>
<div> &CONSTRAINT</div><div> &FIXED_ATOMS</div><div> LIST 53 51 45 43 55 33</div><div> LIST 47 57 5 3 29 27</div><div> List 7 17 31 9</div><div> &END</div><div> &END CONSTRAINT</div>
<div>&END MOTION</div><div>==========================================================================================</div></div><div><br></div><div> Thank you very much!!!!!!!!!!!</div><span class="HOEnZb"><font color="#888888"><div>
<br></div><div><br></div>
<p></p>
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</font></span></blockquote></div><br><br clear="all"><br>-- <br>-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-<br> Ari P Seitsonen / <a href="mailto:Ari.P.S...@iki.fi">Ari.P.S...@iki.fi</a> / <a href="http://www.iki.fi/~apsi/">http://www.iki.fi/~apsi/</a><br>
Physikalisch-Chemisches Institut der Universität Zürich<br> Tel: +41 44 63 55 44 97 / Mobile: +41 79 71 90 935
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