Run RASPA simulation with Rigid MOF structure

[AntonioDouglas]

Hi Prof. Dubbeldam and dear RASPA Community.

I am a beginner in using RASPA.
I am trying to simulate adsorption on a MOF with Monte Carlo, and I am following the manual and the RASPA repository on github as guidance. In order to simulate the structure as rigid, I follow the instructions in the manual in the "Framework parameters" section, so I adopt the parameters:

Framework 0
FrameworkName calf-20
UnitCells 1.0 1.0 1.0
FlexibleFramework no
FrameworkDefinitions framework.def

The last parameter was adopted by recommendation of the manual, which states: "The file is read even when 'FlexibleFramework no' is specified (the reason is that framework bond-dipoles are defined using the 'framework.def' file)".

However, the manual does not contain examples or further details about the framework.def file when the intention is to simulate a rigid structure.
In the RASPA github repository, the examples show the specifications of simulation.input and framework.def for adsorption analysis only when the structure is flexible, thus leaving no further information on how to simulate adsorption in rigid structures.

In an attempt to find a solution, my most reasonable guesses were: 1. Consider that the definition of the rigid structure of the framework described in the content of framework.def was exactly the same as the rigid structure of the molecule, in molecule.def. 2. Consider 0 in all #CoreShells bond BondDipoles UreyBradley bend inv tors configurations improper-torsion bond/bond bond/bend bend/bend stretch/torsion bend/torsion, as stated in the framework.def file used as an example for flexible structures.
Nothing worked.

These and countless other attempts proved fruitless, and most of the time they resulted in the same error log: "Error: Unknown group type (should be 'Flexible' or 'Rigid')", except for guess 1, described above, in which I got the error: "ReturnPseudoAtomNumber: Error!!!! :0.22394", referring to the corresponding value of "Acentric factor [-]", as stated in the edited framework.def file, taking as an example the file for the rigid molecule CO2.def, which is in the RASPA github repository.

With no further ideas on how to proceed, I come to ask for your help, a long-time RASPA user, on how to proceed and solve this problem.

How can I correctly define the parameter to establish that the MOF structure used in the adsorption simulation calculated with Monte Carlo is in fact rigid?

Thank you in advance.

Regards,
Antonio Douglas

[Lingxiao Qin]

I do not think "FlexibleFramework" and "FrameworkDefinitions" have to be explicitly specified when simulating a rigid framework. See the RASPA manual examples of Adsorption isotherm of N2 in a metal-organic framework (MOF), Henry coefficients, enthalpy of adsorption and Adsorption isotherm of CO2 in Cu-BTC for a sample simulation.input file. In addition, you may also compare the input files of these two examples (Diffusion of benzene in rigid IRMOF-1 VS in flexible IRMOF-10) to see that "FlexibleFramework" and "FrameworkDefinitions" are not needed for rigid framework simulation.

In a sum, for your purpose of simulating a rigid structure, it is enough to write

Code Select Expand

Framework 0
FrameworkName calf-20
UnitCells 1.0 1.0 1.0