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#1

General / Download Instagram Reels

Last post by reelsdownload - April 16, 2025, 06:38:25 AM

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#2

General / Re: Help with GCMC Simulation ...

Last post by Elnaz Jangodaz - April 15, 2025, 09:01:03 AM

Hi, I'm experiencing the same issue with water uptake — the calculated uptake is zero at partial pressures corresponding to certain relative humidity values. I noticed something unusual: when I set the external pressure to 101325 Pa at 298 K, the simulation gives an uptake value which is similar to paper results at the saturation point. I put a range of 0-101325 pa for external pressure, the resulting isotherm shows the same uptake trend and point, but now with p₀ = 101325 Pa instead of 31.7 kPa, which is the correct saturation pressure. I'm not sure why the uptake appears at such a high pressure, especially since water should already be in liquid form at 101325 Pa. Let me know if you've figured out what the issue might be.

#3

Input files and parameters / CB/CFC Monte Carlo Input File

Last post by hooman - April 11, 2025, 06:47:04 PM

Dear Prof. Dubbeldam, all,

I want to simulate adsorption in MOFs using CB/CFCMC ensemble, but I'm not sure if I'm doing it the right way.
I have done it with the following settings, but although the number of cycles are relatively large and I've done a similar simulation with GCMC, I still see points in the isotherm where the uptake is not consistently increasing with partial pressure and it's at points lower than CBGCMC uptake.

Thank you very much.
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#4

Input files and parameters / Gibbs Ensemble Monte Carlo (GE...

Last post by hooman - April 11, 2025, 06:17:51 PM

Dear Prof. Dubbeldam, all,

I'm simulating adsorption in a MOF model system using the GEMC ensemble in RASPA. I have several questions regarding the methodology and input file;

1- Should the properties of the reservoir box (size, number of molecules) change in accordance to the pressure point (P as in P/Psat) in the isotherm?
2- How do I fix the volume of the MOF simulation box and how would that translate in thermodynamic terms?
3- How should I choose the proper volume move probability?

Thank you very much.

#5

General / Re: Help with GCMC Simulation ...

Last post by had-sham - April 09, 2025, 11:31:46 AM

Hello everyone,

I reviewed the RASPA simulation output and noticed that in the input block, the density and compressibility of water are reported as 848.3 kg/m³ and 0.0000257130, which are values for the liquid phase. Since we're simulating the adsorption of water vapor, how can I resolve this issue?

Thanks!

#6

General / Help with GCMC Simulation for ...

Last post by had-sham - April 06, 2025, 05:10:42 PM

Hi Dear RASPA Community,

I am a beginner in using RASPA and currently working on GCMC simulations for water adsorption in a MOF. I'm trying to reproduce data from the literature, where the reported water uptake at maximum relative humidity (i.e., adsorption from air) is around 30 g/g. However, in my simulation, the uptake is significantly lower—close to zero.

I have reviewed my input files multiple times but haven't been able to identify the issue. I would greatly appreciate it if someone could take a look at my simulation setup and provide guidance.
My input files are attached. For reference, the attached files are described below:

File "perfect_charge.def": The CIF file of the MOF structure. Partial charges were obtained using charge equilibration in RASPA.

File "Tip4p": The water molecule definition file.

Thank you very much for your support!

Best regards,

#7

Input files and parameters / Question about Gibbs simulatio...

Last post by Kimchen - March 20, 2025, 12:32:28 PM

Hallo everyone, i got an error message of:WARNING: ENERGY DRIFT (INTERNAL CONSISTENCY ERROR IN THE CODE), THE SIMULATION RESULTS ARE WRONG!! in Gibbe ensemble simulation of H2.
Here is my parameters:
force field mixing
# general rule for shifted vs truncated
truncated
# general rule tailcorrections
yes
# number of defined interactions
2
# type interaction, parameters.    IMPORTANT: define shortest matches first, so that more specific ones overwrites these
H_h2           none                                    //
H_com          FEYNMAN HIBBS LENNARD JONES    36.7      2.958        // idem
# general mixing rule for Lennard-Jones
Lorentz-Berthelot
pseudo_atom:
#number of pseudo atoms
2
#type      print   as    chem  oxidation   mass        charge   polarization B-factor radii  connectivity anisotropic anisotropic-type   tinker-type        0
H_h2       yes     H     H     0           0.0         0.468    0.0          1.0      0.31   0            0           relative           0
H_com      no      H     -     0           2.016      -0.936    0.0          1.0      0.31   0            0           relative           0
H2.def:
# critical constants: Temperature [T], Pressure [Pa], and Acentric factor [-]
33.19
1293000.0
-0.22
# Number Of Atoms
3
# Number Of Groups
1
# H2-group
rigid
# number of atoms
3
# atomic positions
0 H_h2    0.0           0.0           0.37
1 H_com   0.0           0.0           0.0
2 H_h2    0.0           0.0          -0.37
# Chiral centers Bond  BondDipoles Bend  UrayBradley InvBend  Torsion Imp. Torsion Bond/Bond Stretch/Bend Bend/Bend Stretch/Torsion Bend/Torsion IntraVDW IntraCoulomb
               0    2            0    0            0       0        0            0         0            0         0               0            0        0            0
# Bond stretch: atom n1-n2, type, parameters
0 1 RIGID_BOND
1 2 RIGID_BOND
# Number of config moves
0
Does anyone know whats the problem?

#8

General / What is the source of GenericM...

Last post by Sipra Mohapatra - March 13, 2025, 06:47:54 AM

Hii all,

Is GenericMOF FF safe for MOF simulations? I am not finding any citation for the force field. Is it the modified version of UFF/Dreiding? Can someone explain?

#9

Announcements / Re: RASPA workshop announced (...

Last post by Sipra Mohapatra - March 12, 2025, 04:41:16 PM

Is there a possibility of a RASPA workshop being held in 2025?

#10

Input files and parameters / Ethylene with TraPPe UA2 probl...

Last post by CheMiNuB - March 08, 2025, 10:38:21 PM

Im trying to simulate the adsorption of c2h4 on mofs  using different models
only with TraPPe_UA2 i keep getting the error

Simulation finished,  1 warnings
WARNING: ENERGY DRIFT (INTERNAL CONSISTENCY ERROR IN THE CODE), THE SIMULATION RESULTS ARE WRONG!!

Here's my Model

# critical constants: Temperature [T], Pressure [Pa], and Acentric factor [-]
282.4
5032000.0
0.085
# Number Of Atoms
4
# Number Of Groups
1
# Alkane-group
Rigid
# number of atoms
4
# atomic positions
0 CH2_sp2 0.0   0.0  0.0
1 CH2_sp2 1.70  0.0  0.0
2 D       0.85  0.65 0.0
3 D       0.85 -0.65 0.0
# Chiral centers Bond  BondDipoles Bend  UrayBradley InvBend  Torsion Imp. Torsion Bond/Bond Stretch/Bend Bend/Bend Stretch/Torsion Bend/Torsion IntraVDW IntraCoulomb
               0    2            0    0            0       0        0            0         0            0         0               0            0        0            0
# Bond stretch: atom n1-n2, type, parameters
0 1 RIGID_BOND
2 3 RIGID_BOND
# Number of config moves
0

Anybody has any ideas ?