[Pw_forum] Huge dispersion energy
Venkataramana Imandi
venkataramana.imandi at gmail.com
Sun Oct 11 07:27:49 CEST 2015
Dear Ari Paavo Seitsonen
You are exactly correct, I am extracting dispersion energy.
I calculated binding or adsorption energy, it was 16.6 kJ/mol, which is
close to physisorption well (I think that the depth of physisorption well
is the binding or adsorption energy). The energy of physisorption well has
a depth of 4-12 kJ/mol from experiments.
If the depth of physisorption well is not binding energy, then there is no
exact experimental information of binding energy of methane on top of
Ir(111) surface.
However, one Ir10 cluster calculations (J.Catal, 185, 12-22, 1999) has
reported that binding energy was 13.5 kJ/mol.
Anyway, you mentioned that dispersion energy is not defined with vdW-DF,
then what is specialty of vdW-DF functionals than grimme-d2 or DFT-D of
semiempirical corrections.
This is just I would like to know more about these functionals.
Thanks for response.
On Sat, Oct 10, 2015 at 6:36 PM, Venkataramana Imandi <
venkataramana.imandi at gmail.com> wrote:
> Dear QE users,
>
> The geometry of methane molecule on the top of Iridium slab is relaxed.
> In that relaxed geometry, methane molecule is sitting 4.32 angstroms on
> the top of Iridium atom, which is exactly same as Henkelman results (prl,
> 86,664-667,2001).
> The total energy of relaxed geometry is -5861698.6 kJ/mol. (val1)
> I took that relaxed geometry coordinates and then I applied dispersion
> interactions of that configuration only. (input file is attached,
> Dispersion interactions with non-local functional)
> The total energy with dispersion interactions is -5893444.5 kJ/mol. (val2)
> The difference of val2 and val1 is -31745.9 kJ/mol.
> Moreover, I used grimme-d2 dispersion interactions (commenting out
> input_dft='vdw-df') , then total energy is -5876733.8 kJ/mol. (val3)
> The difference of val3 and val1 is -15035.2 kJ/mol.
>
> I want to reproduce the results of Henkelman. In these results the total
> energy difference between with dispersion and without dispersion is roughly
> 10 kJ/mol.
>
> I am unable to find out where the mistake is. are input parameters correct
> in the input file (input file is attached).
> Thanks in advance for any suggestions and help.
>
> &control
> calculation='scf',
> prefix='ir_ch',
> nstep=5000,
> etot_conv_thr=1.0D-5,
> forc_conv_thr=1.0D-4,
> pseudo_dir = '/home/venkat/ORR1/PPS1'
> /
> &system
> ibrav=0,
> nat=77,
> ntyp=3,
> ecutwfc = 35.D0,
> ecutrho=350.D0,
> nosym=.true.,
> occupations='smearing',
> smearing='m-p',
> degauss=0.07D0,
> input_dft='vdw-df'
> ! vdw_corr='grimme-d2',
> ! london_s6=1.07
> /
> &electrons
> electron_maxstep=2000,
> diagonalization='david',
> mixing_beta = 0.7D0,
> conv_thr = 1.0D-8,
> scf_must_converge=.true.
> mixing_mode = 'local-TF' ,
> startingpot = 'atomic' ,
> startingwfc = 'atomic' ,
> /
> ATOMIC_SPECIES
> C 12.0107 C.pw91-n-rrkjus_psl.0.1.UPF
> H 1.00794 H.pw91-rrkjus_psl.0.1.UPF
> Ir 192.217 Ir.pw91-n-rrkjus_psl.0.2.3.UPF
>
> CELL_PARAMETERS angstrom
> 8.1437488 0.00000000 0.00000000
> 0.0000000 9.40359112 0.00000000
> 0.0000000 0.00000000 23.29868610
>
> ATOMIC_POSITIONS angstrom
> C 2.503115327 3.097048163 11.006076080
> H 2.559820746 3.082197974 12.098882130
> H 3.514431623 3.102156372 10.587895658
> H 1.968544691 2.208651619 10.655809495
> H 1.969648626 3.995188986 10.679852435
> Ir 6.786984985 5.377327249 6.690210403
> Ir 5.429761742 7.728578222 6.689802926
> Ir 5.429746349 4.650752045 4.467294416
> Ir 6.787041667 7.001529230 4.467393130
> Ir 5.429722714 6.240972848 2.221357938
> Ir 6.787038463 8.591738181 2.221368427
> Ir 4.072711710 5.377961700 6.689813188
> Ir 2.715081868 7.728500982 6.690023074
> Ir 2.715156078 4.650646584 4.467806211
> Ir 4.072348477 7.001642794 4.467556443
> Ir 2.715176306 6.240724087 2.221365994
> Ir 4.072433521 8.591776168 2.221423434
> Ir 1.357573198 5.378108129 6.689576660
> Ir 0.000492878 7.728616956 6.689942506
> Ir 0.000525907 4.650701814 4.467367485
> Ir 1.357873390 7.001703168 4.467414495
> Ir 0.000608784 6.240914105 2.221325333
> Ir 1.357921734 8.591831421 2.221404032
> Ir 6.786998124 0.675884041 6.690188874
> Ir 5.429896882 3.027018594 6.689570921
> Ir 5.429772024 -0.051058629 4.467515860
> Ir 6.787070082 2.299704238 4.467484822
> Ir 5.429712380 1.539122018 2.221560696
> Ir 6.787043197 3.889907517 2.221290932
> Ir 4.072528886 0.675690271 6.689950314
> Ir 2.715144414 3.026427071 6.690591842
> Ir 2.715184457 -0.051003432 4.467559212
> Ir 4.072256200 2.299934774 4.467754385
> Ir 2.715207159 1.539060724 2.221195718
> Ir 4.072485784 3.889991322 2.221325430
> Ir 1.357730275 0.675696976 6.689663193
> Ir 0.000402805 3.026907165 6.689722063
> Ir 0.000465563 -0.051073916 4.467501695
> Ir 1.358021383 2.299936261 4.467561579
> Ir 0.000648125 1.539099393 2.221473282
> Ir 1.357895673 3.890022499 2.221300840
> Ir 6.787097597 5.514587239 -0.053952363
> Ir 5.429839890 7.865526352 -0.054013090
> Ir 5.429858365 4.753810264 -2.300201608
> Ir 6.787129254 7.104615003 -2.300285157
> Ir 5.429861628 6.377672836 -4.522696367
> Ir 6.787164952 8.728667505 -4.522668683
> Ir 4.072555282 5.514603378 -0.054059495
> Ir 2.715247652 7.865432797 -0.054052327
> Ir 2.715268974 4.753802500 -2.300196550
> Ir 4.072605680 7.104724090 -2.300233141
> Ir 2.715285443 6.377796366 -4.522582334
> Ir 4.072611873 8.728652635 -4.522585040
> Ir 1.357905576 5.514612078 -0.054088067
> Ir 0.000614738 7.865518063 -0.054021354
> Ir 0.000674468 4.753790149 -2.300199617
> Ir 1.357948399 7.104749029 -2.300179393
> Ir 0.000728657 6.377731702 -4.522632394
> Ir 1.357977623 8.728636821 -4.522521749
> Ir 6.787108599 0.812829365 -0.053922294
> Ir 5.429809095 3.163686103 -0.054046362
> Ir 5.429904914 0.052053316 -2.300169041
> Ir 6.787129723 2.402910250 -2.300245521
> Ir 5.429851128 1.675953619 -4.522630149
> Ir 6.787162294 4.026862240 -4.522704329
> Ir 4.072535289 0.812764973 -0.054035020
> Ir 2.715242101 3.163709989 -0.054027559
> Ir 2.715286429 0.051968519 -2.300226402
> Ir 4.072562838 2.402884356 -2.300163576
> Ir 2.715283877 1.675941416 -4.522610797
> Ir 4.072578475 4.026812582 -4.522580048
> Ir 1.357957951 0.812783022 -0.054064552
> Ir 0.000656686 3.163662587 -0.054050148
> Ir 0.000629358 0.052042760 -2.300145024
> Ir 1.357985927 2.402907066 -2.300151863
> Ir 0.000726255 1.675939186 -4.522594246
> Ir 1.358007815 4.026800160 -4.522546893
>
> K_POINTS gamma
>
> venkataramana
> PhD student
> IIT Bombay
>
>
--
venkataramana
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