Messages

Hello everyone
In RASPA name, what does each capital letter mean?
I appreciate all your kind responses.
Thank you
Sara

Thanks a lot for your great reply. Do you mean by the fluctuations of MSD, I can comprise diffusion coefficient? I don't understand the meaning of MD path.

Dear Prof. Dubbeldum

Is there any method to get movies from MD results to show that the molecules with higher diffusion coefficient have higher speed in the framework than molecules with lower diffusion coefficient?

Dear Prof.Dubbeldum

I calculated diffusion coefficient for a binary mixture. The slope of MSD is negative and therefore diffusion coefficient is negative ( for example slope= -0.014 for one or both of species ). Could you please explain the physical meaning of that observation?
I will be so grateful if you guide me.

Dear Prof.Dubbeldum

I calculated diffusion coefficient for a binary mixture. The slope of MSD is negative and therefore diffusion coefficient is negative ( for example slope= -0.014 for one or both of species ). Could you please explain the physical meaning of that observation?
I will be so grateful if you guide me.

Dear Dr. Dubbeldum
I am using RASPA to calculate propane/propene selectivity of pure silica zeolite LTA using the following code. In output absolute loading for both propane and propene is positive, But excess loading is negative.  Then I tried this simulation in 1 bar pressure, But excess loading is negative. Thanks a lot for guiding me.
SimulationType                MonteCarlo
NumberOfCycles                100000
NumberOfInitializationCycles  10000
PrintEvery                    1000
RestartFile                   no

ContinueAfterCrash            no
WriteBinaryRestartFileEvery   500

Forcefield                    local
UseChargesFromCIFFile         yes

Framework 0
FrameworkName Framework_0_final_1_1_1
UnitCells 3 3 3
HeliumVoidFraction 0.460673
ExternalTemperature 308.37
ExternalPressure 1970000
Movies yes
WriteMoviesEvery 1000

Component 0 MoleculeName               propene
            MoleculeDefinition         local
            IdealGasRosenbluthWeight   1.0
            MoleFraction               0.91
            TranslationProbability     0.5
            RotationProbability        0.5
            ReinsertionProbability     0.5
            IdentityChangeProbability  1.0
            NumberOfIdentityChanges    2
            IdentityChangesList        0 1
            SwapProbability            1.0
            CreateNumberOfMolecules    0
           
Component 1 MoleculeName               propane
            MoleculeDefinition         local
            IdealGasRosenbluthWeight   1.0
            MoleFraction               0.09
            TranslationProbability     0.5
            RotationProbability        0.5
            ReinsertionProbability     0.5
            IdentityChangeProbability  1.0
            NumberOfIdentityChanges    2
              IdentityChangesList      0 1
            SwapProbability            1.0
            CreateNumberOfMolecules    0
           

Dear Dr. Dubbeldum
Thanks a lot for your response. I compared my results with experimental data. The results for liquid density are accurate at all temperatures with the error of 1%, but the results for vapor density are not accurate with the error of 20%. When I compared my results with the results of a paper ,published in 1998, I understood that they could not get the accurate results for vapor density using TraPPE-UA.
What is the reason that vapor density is not achieved? Is not it because of the length of boxes?
SimulationType                MonteCarlo

NumberOfCycles                100000
NumberOfInitializationCycles  10000

RestartFile                   no
ContinueAfterCrash            no
WriteBinaryRestartFileEvery   1000

PrintEvery                    1000
PrintPropertiesEvery          1000

ChargeMethod                  Ewald
EwaldPrecision                1e-5
Forcefield                    TraPPE-UA
CutOffVDW                     14
CutOffChargeCharge            14

Box 0
BoxLengths 30 30 30
BoxAngles 90 90 90
ExternalTemperature 200

Movies                        yes
WriteMoviesEvery              1000

ComputeEnergyHistogram        yes
ComputeNumberOfMoleculesHistogram      yes
ComputeMolecularPressure      yes

Box 1
BoxLengths 30 30 30
BoxAngles 90 90 90
ExternalTemperature 200

Movies                        yes
WriteMoviesEvery              1000

ComputeEnergyHistogram        yes
ComputeNumberOfMoleculesHistogram      yes
ComputeMolecularPressure      yes

GibbsVolumeChangeProbability 0.05

Component 0 MoleculeName             propane
            MoleculeDefinition       TraPPE-UA
            TranslationProbability   0.5
            RotationProbability      0.5
            ReinsertionProbability   0.5
            GibbsSwapProbability     0.5
            CreateNumberOfMolecules  100 100
           
 

Dear Dr. Dubbeldam
I prepare the attached code to calculate vapor liquid equilibrium and the density of vapor and liquid phases for propane using TraPPE-UA force field parameters. But the vapor density is not accurate. I changed the number of molecules so many times and ran the code, but I did not get the right answer. Would you please guide me? Thank you for your kindness and support.
SimulationType                MonteCarlo
NumberOfCycles                25000
NumberOfInitializationCycles  5000
PrintEvery                    1000
RestartFile                   no

Forcefield                    TraPPE-UA
CutOff                        14

Box 0
BoxLengths 30 30 30
BoxAngles 90 90 90
ExternalTemperature 344.0

Box 1
BoxLengths 30 30 30
BoxAngles 90 90 90
ExternalTemperature 344.0

GibbsVolumeChangeProbability 0.1

Component 0 MoleculeName             propane
            StartingBead             1
            MoleculeDefinition       TraPPE-UA
            TranslationProbability   0.5
            RotationProbability      0.5
            ReinsertionProbability   0.5
            GibbsSwapProbability     0.5
            CreateNumberOfMolecules  185 15

Dear Professor Dubbeldam,
I have solved the problem. I want to block inaccessible pores for different zeolites when they adsorb propane or propene. In zeo++ website, the related command is "  ./network -ha -block probe_radius num_samples input_structure.cssr  ". I set a value instead of term "probe_radius" for example 0.5,1,1.5, but the output file is just zero. I will be very grateful if you can guide me.
Thanks a lot
best regards

Dear Professor Dubbeldam,
I have installed zeo++, and I have the cssr file from openbabel, when I run the command "./network -ha -block probe_radius num_samples input_structure.cssr" this error is shown: "voro++: periodic cell computation failed". What should I do? please guide me.
Thanks a lot
best regards