Hello Everyone, In trying to validate the computational methods and configuration of my system for a desired study, the adsorption energies I obtained upon computation seems to be about twice the value of what i was expecting.
This is adsorption of CO on nickel surface sites on Ni-111 surface structure. Literature mentions the adsorption energies on the sites top, bridge, fcc and hcp to be: -137.9, -159.0, -163.7 and -164.6 kJ/mol respectively, whereas i'm getting -305.03, -328.04, -339.56 and -409.55 kJ/mol respectively. The qualitative trend seems to exists where the hcp site is the most energetically favourable site for adsorption in both literature and my study, however, quantitatively, my values are too larger. I adsorb the molecule on only one side of the slab. Do I have to adsorb on both sides of the slab in mirror positions to handle dipole moment perpendicular to the surface due to adsorption? What could the reason or problem be? Please find attached the input files of my hcp site calculation for your perusal. Thank you. Kind Regards, Elliot -- Elliot S. Menkah, AMRSC Research Student - Computational Chemistry/ Computational Material Science Theoretical and Computational Chemistry Dept. of Chemistry Kwame Nkrumah UNiversity of Sci. and Tech. Kumasi Ghana Tel: +233 243-055-717 Alt Email: esmen...@knust.edu.gh elliotsmen...@gmail.com elliotsmen...@hotmail.com
&CONTROL title = 'Ni-2x2-111-6L-MD-CO-3fold-fcc' , calculation = 'relax' , restart_mode = 'from_scratch' , outdir = './tmp' , pseudo_dir = '/home/eliot/pseudo' , prefix = 'ni-111-2x2-6L-MD-CO-3fold-fcc', tstress = .true. , tprnfor = .true. , / &SYSTEM ibrav = 0, celldm(1) = 1.88972599, nat = 98, ntyp = 3, ecutwfc = 40, ecutrho = 480, occupations='smearing', smearing='mp', degauss=0.05, nbnd=560, nspin=2, starting_magnetization(1)=0.5, / &ELECTRONS conv_thr = 1.0D-6, mixing_mode = 'local-TF' / &IONS / ATOMIC_SPECIES Ni 58.6934 Ni.pbe-nd-rrkjus.UPF C 12.011 C.pbe-rrkjus.UPF O 15.999 O.pbe-rrkjus.UPF ATOMIC_POSITIONS (alat) Ni 1.245247692 0.718944090 0.015868783 0 0 0 Ni 2.490495415 2.875776414 0.015868783 0 0 0 Ni 3.735743138 0.718944090 0.015868783 0 0 0 Ni 4.980990830 2.875776397 0.015868355 0 0 0 Ni 1.245247472 3.594720360 2.023998778 0 0 0 Ni 2.490495415 5.751553065 2.023998778 0 0 0 Ni 3.735743358 3.594720360 2.023998778 0 0 0 Ni 4.980990830 5.751552793 2.023999431 0 0 0 Ni 1.245247844 6.470496971 4.059965132 0 0 0 Ni 2.490495415 8.627329032 4.059965132 0 0 0 Ni 3.735742986 6.470496971 4.059965132 0 0 0 Ni 4.980990830 8.627329190 4.059964979 0 0 0 Ni 1.246709841 9.346680057 6.089903308 Ni 2.491049866 11.503272365 6.094695989 Ni 3.736309279 9.347499400 6.091839589 Ni 4.981632933 11.503215624 6.094592854 Ni 1.251397606 12.222515270 8.130528230 Ni 2.493872076 14.374876735 8.130574795 Ni 3.736773669 12.222408715 8.121452049 Ni 4.979701257 14.375516889 8.129406603 Ni 1.243830060 15.097651794 10.124780901 Ni 2.490567863 17.254288878 10.125834084 Ni 3.737277529 15.124361083 10.124533866 Ni 4.983701851 17.254644423 10.125942272 Ni 3.735743107 5.032608685 0.015868783 0 0 0 Ni 4.980990830 7.189441009 0.015868783 0 0 0 Ni 6.226238553 5.032608685 0.015868783 0 0 0 Ni 7.471486245 7.189440992 0.015868355 0 0 0 Ni 3.735742887 7.908384955 2.023998778 0 0 0 Ni 4.980990830 10.065217660 2.023998778 0 0 0 Ni 6.226238773 7.908384955 2.023998778 0 0 0 Ni 7.471486245 10.065217388 2.023999431 0 0 0 Ni 3.735743259 10.784161566 4.059965132 0 0 0 Ni 4.980990830 12.940993627 4.059965132 0 0 0 Ni 6.226238401 10.784161566 4.059965132 0 0 0 Ni 7.471486245 12.940993785 4.059964979 0 0 0 Ni 3.736296794 13.660278999 6.094631584 Ni 4.981840953 15.816305949 6.089805212 Ni 6.225869615 13.659635984 6.091567601 Ni 7.472468264 15.816767005 6.089493887 Ni 3.736896631 16.534686190 8.122356924 Ni 4.983572283 18.693711643 8.122423344 Ni 6.227530794 16.536159378 8.121678221 Ni 7.475062891 18.697174708 8.130314215 Ni 3.737430863 19.413420133 10.125793472 Ni 4.981744277 21.571270847 10.124719443 Ni 6.205422793 19.399131231 10.125043022 Ni 7.471688751 21.569920708 10.195553976 Ni 6.226238522 0.718944090 0.015868783 0 0 0 Ni 7.471486245 2.875776414 0.015868783 0 0 0 Ni 8.716733968 0.718944090 0.015868783 0 0 0 Ni 9.961981660 2.875776397 0.015868355 0 0 0 Ni 6.226238302 3.594720360 2.023998778 0 0 0 Ni 7.471486245 5.751553065 2.023998778 0 0 0 Ni 8.716734188 3.594720360 2.023998778 0 0 0 Ni 9.961981660 5.751552793 2.023999431 0 0 0 Ni 6.226238674 6.470496971 4.059965132 0 0 0 Ni 7.471486245 8.627329032 4.059965132 0 0 0 Ni 8.716733816 6.470496971 4.059965132 0 0 0 Ni 9.961981660 8.627329190 4.059964979 0 0 0 Ni 6.225973474 9.346546538 6.089989264 Ni 7.471621945 11.503853546 6.089790972 Ni 8.717377404 9.346452757 6.090683436 Ni 9.963257320 11.503913751 6.089966258 Ni 6.222932962 12.222252478 8.129332507 Ni 7.470857119 14.378343414 8.121361647 Ni 8.718059007 12.222626174 8.121568843 Ni 9.964518686 14.378185126 8.121779387 Ni 6.230847493 15.098640938 10.124112763 Ni 7.474569271 17.253185302 10.124621946 Ni 8.718011778 15.098252280 10.124628469 Ni 9.961558698 17.252773665 10.124595778 Ni 8.716733937 5.032608685 0.015868783 0 0 0 Ni 9.961981660 7.189441009 0.015868783 0 0 0 Ni 11.207229383 5.032608685 0.015868783 0 0 0 Ni 12.452477075 7.189440992 0.015868355 0 0 0 Ni 8.716733717 7.908384955 2.023998778 0 0 0 Ni 9.961981660 10.065217660 2.023998778 0 0 0 Ni 11.207229603 7.908384955 2.023998778 0 0 0 Ni 12.452477075 10.065217388 2.023999431 0 0 0 Ni 8.716734089 10.784161566 4.059965132 0 0 0 Ni 9.961981660 12.940993627 4.059965132 0 0 0 Ni 11.207229231 10.784161566 4.059965132 0 0 0 Ni 12.452477075 12.940993785 4.059964979 0 0 0 Ni 8.717314947 13.660636235 6.089490100 Ni 9.962110380 15.816726745 6.089592695 Ni 11.208740061 13.659631527 6.091948135 Ni 12.452767496 15.816182474 6.090053196 Ni 8.717575346 16.537924157 8.121748080 Ni 9.960512304 18.696990663 8.130311275 Ni 11.207967602 16.535790646 8.121816703 Ni 12.452489216 18.693540783 8.122210426 Ni 8.718626602 19.409894146 10.195007369 Ni 9.966868016 21.570687486 10.192425525 Ni 11.231381306 19.398971630 10.124254459 Ni 12.455857855 21.571478700 10.123984004 C 8.723467559 20.851726334 11.508948792 O 8.727741803 20.853291675 12.699898222 K_POINTS automatic 5 5 1 0 0 0 CELL_PARAMETERS +9.9619816602 +0.0000000000 +0.0000000000 +4.9809908302 +8.6273291898 +0.0000000000 -0.0000000000 +0.0000000000 +24.2008859472
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