Hi Prof. Dubbeldam,
I'm using raspa for hydrogen adsorption simulation in ZIF-8, I had edited the input file and force field file of MOF-5 given in the examples for the using ZIF-8 (lennard jones parameters are also changed according to ZIF-8) as adsorbate . After running the simulation i got high adsorption capacities of hydrogen than reported in literature, it happened for 77K and 300K. I would like to know what might be the problem in this simulation.
[b]My input file [/b]
SimulationType MonteCarlo
NumberOfCycles 50000
NumberOfInitializationCycles 1000
PrintEvery 2000
Forcefield GenericMOFs1
Framework 0
FrameworkName ZIF-8
UnitCells 1 1 1
HeliumVoidFraction 0.484279
ExternalTemperature 300
ExternalPressure 5e5 10e5 15e5 20e5 30e5 40e5 50e5 60e5 10e6 20e6
Component 0 MoleculeName H2
MoleculeDefinition TraPPE
TranslationProbability 1
ReinsertionProbability 1
SwapProbability 1
CreateNumberOfMolecules 0
I edited only forcefield mixing.def file and left forcefield and psuedo atoms.def file as it is
Edited force field is
# general rule for shifted vs truncated
shifted
# general rule tailcorrections
no
# number of defined interactions
55
# type interaction, parameters. IMPORTANT: define shortest matches first, so that more specific ones overwrites these
O_ lennard-jones 30.19 3.12
N_ lennard-jones 34.72 3.26256
C_ lennard-jones 52.84 3.4299
F_ lennard-jones 36.4834 3.0932
B_ lennard-jones 47.8058 3.58141
P_ lennard-jones 161.03 3.69723
S_ lennard-jones 173.107 3.59032
Cl_ lennard-jones 142.562 3.51932
Br_ lennard-jones 186.191 3.51905
H_ lennard-jones 22.14 2.57
Zn_ lennard-jones 62.3992 2.46155
Be_ lennard-jones 42.7736 2.44552
Cr_ lennard-jones 7.54829 2.69319
Fe_ lennard-jones 6.54185 2.5943
Mn_ lennard-jones 6.54185 2.63795
Cu_ lennard-jones 2.5161 3.11369
Co_ lennard-jones 7.04507 2.55866
Ga_ lennard-jones 208.836 3.90481
Ti_ lennard-jones 8.55473 2.8286
Sc_ lennard-jones 9.56117 2.93551
V_ lennard-jones 8.05151 2.80099
Ni_ lennard-jones 7.54829 2.52481
Zr_ lennard-jones 34.7221 2.78317
Mg_ lennard-jones 55.8574 2.69141
Ne_ lennard-jones 21.1352 2.88918
Ag_ lennard-jones 18.1159 2.80455
In_ lennard-jones 301.428 3.97608
Cd_ lennard-jones 114.734 2.53728
Sb_ lennard-jones 225.946 3.93777
Te_ lennard-jones 200.281 3.98232
Al_ lennard-Jones 155.998 3.91105
Si_ lennard-Jones 155.998 3.80414
He lennard-jones 10.9 2.64
CH4_sp3 lennard-jones 148 3.73
CH3_sp3 lennard-jones 108.0 3.76
CH2_sp3 lennard-jones 56.0 3.96
CH_sp3 lennard-jones 17.0 4.67
C_sp3 lennard-jones 0.8 6.38
H_com lennard-jones 30 2.58
H_h2 lennard-jones 36.7 2.59
O_co2 lennard-jones 79.0 3.05
C_co2 lennard-jones 27.0 2.80
C_benz lennard-jones 30.70 3.60
H_benz lennard-jones 25.45 2.36
N_n2 lennard-jones 36.0 3.31
N_com none
Ow lennard-jones 89.633 3.097
N_dmf lennard-jones 80.0 3.2
Co_dmf lennard-jones 50.0 3.7
Cm_dmf lennard-jones 80.0 3.8
O_dmf lennard-jones 100.0 2.96
H_dmf lennard-jones 8.0 2.2
Ar lennard-jones 119.8 3.34
Kr lennard-jones 166.4 3.636
Xe lennard-jones 221.0 4.1
# general mixing rule for Lennard-Jones
Lorentz-Berthelot
Thanks.
Higher adsorption capacity compared to what? experiments? other simulations?
For the first, you need to make sure you use a reliable force field and a structure that corresponds to the experiments (taking inaccessibility for example into account). For the latter, you need to make sure you do the simulations exactly as published in the literature.
Thanks for the reply,
I compared with the experiments and i want to make sure my force fields and input file are correct because in the warnings of each simulation it shows max 50 interactions are missing which are Eg: Zn_H_O, C1_C2_Zn etc.
Near 77K in the literature mentioned that quantum effects are considered to get accurate experimental results. Is it possible to include that in raspa?
The forcefield and molecules present in RASPA are examples. For your system you need to define your own force field (for the adsorbate, the ZIF-8, and the cross-interactions). All relevant interactions needs to be defined.