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Direct energy comparison between gRASPA and RASPA-2!

Introduction

  • One always wonders: can we rely on the energies calculated by gRASPA?
  • 🎺 We can (try to...) confirm with RASPA-2!
  • We will do TIP4P adsorption in a MOF!

Preparations

  • TIP4P.def
    • This is the molecule definition file
  • MOF.cif
    • This is the MOF definition file in the CIF format (Currently only P1 symmetry allowed)
  • force_field_mixing_rules.def
  • pseudo_atoms.def
  • Restart File
    • In RASPA-2, name the restart file according to the structure, unit cells, temperature, and pressure (order matters).
      • like "RestartInitial/System_0/restart_MOF_4.2.2_298.000000_943"
      • 📝 RASPA-2 uses scientific notation for numbers greater than 1 million: use "1e+06" for 1 million.
    • In gRASPA, just name it "restartfile"
      • like "RestartInitial/System_0/restartfile"

✍ simulation.input

  • Basically, you read the restart file, and run 0 cycles/steps.
gRASPA RASPA-2 
NumberOfInitializationCycles 0
NumberOfEquilibrationCycles  0
NumberOfProductionCycles     0

UseMaxStep  yes
MaxStepPerCycle 1

RestartFile yes
RandomSeed  0

NumberOfTrialPositions 10
NumberOfTrialOrientations 10

NumberOfBlocks 1
AdsorbateAllocateSpace 10240
NumberOfSimulations 1
SingleSimulation yes

DifferentFrameworks no
InputFileType cif
FrameworkName qmof-71d1286
UnitCells 0 4 2 2

ChargeMethod Ewald
UseChargesFromCIFFile yes
Temperature 298
Pressure    943

OverlapCriteria 1e5
CutOffVDW 12.8
CutOffCoulomb 12.8
EwaldPrecision 1e-6

Component 0 MoleculeName             TIP4P
            IdealGasRosenbluthWeight 1.0
            FugacityCoefficient      1.0
            TranslationProbability   1.0
            RotationProbability      1.0
            ReinsertionProbability   1.0
            SwapProbability          1.0
            RunTMMC no
            UseBiasOnMacrostate no
            TMMCMin 0
            TMMCMax 10
            CreateNumberOfMolecules  0



SimulationType        MonteCarlo
NumberOfCycles        0
NumberOfInitializationCycles 0

PrintEvery                    1

RestartFile                   yes
ContinueAfterCrash            no

Framework 0
FrameworkName                      qmof-71d1286
UnitCells                          4 2 2
ExternalTemperature               298.0
ExternalPressure       943

Forcefield                          local
RemoveAtomNumberCodeFromLabel       yes
UseChargesFromCIFFile               yes
ChargeMethod                        Ewald
EwaldPrecision                      1e-6
CutOffVDW                           12.8
CutOffCoulomb                       12.0

Component 0 MoleculeName              TIP4P
            StartingBead              0
            MoleculeDefinition        local
            FugacityCoefficient       1.0
            TranslationProbability    0.0
            RotationProbability       0.0
            ReinsertionProbability    0.0
            SwapProbability           0.0
            CreateNumberOfMolecules   0

Result Comparison

gRASPA RASPA-2 
========================================================================
 *** FINAL STAGE ***
========================================================================
VDW [Host-Host]:            0.00000 (0.00000 [K])
VDW [Host-Guest]:           -165480.57010 (-199027.50030 [K])
VDW [Guest-Guest]:          235009.52229 (282651.65960 [K])
Real Coulomb [Host-Host]:   0.00000 (0.00000 [K])
Real Coulomb [Host-Guest]:  -437087.31113 (-525695.52363 [K])
Real Coulomb [Guest-Guest]: -1373657.28204 (-1652130.97197 [K])
Ewald [Host-Host]:          589637.95832 (709171.89165 [K])
Ewald [Host-Guest]:         -14747.79106 (-17737.52645 [K])
Ewald [Guest-Guest]:        -41543.41156 (-49965.26996 [K])
DNN Energy:                 0.00000 (0.00000 [K])
Tail Correction Energy:     0.00000 (0.00000 [K])
Total Energy:               -1207868.88529 (-1452733.24107 [K])



Current (full final energy) Energy Status
===========================================================================
Host/Adsorbate energy:                                  -742474.08208755
        Host/Adsorbate VDW energy:                              -199028.66021012
        Host/Adsorbate Coulomb energy:                          -543445.42187744
        Host/Adsorbate charge-charge Real energy:               -520688.45228316
        Host/Adsorbate charge-charge Fourier energy:             -22756.96959428
        Host/Adsorbate charge-bonddipole Real energy:                 0.00000000
        Host/Adsorbate charge-bonddipole Fourier energy:              0.00000000
        Host/Adsorbate bondipole-bonddipole Real energy:              0.00000000
        Host/Adsorbate bondipole-bonddipole Fourier energy:           0.00000000
...
Adsorbate/Adsorbate energy:                                 -1419485.34470171
        Adsorbate/Adsorbate VDW energy:                               282651.85973471
        Adsorbate/Adsorbate Coulomb energy:                         -1702137.20443643
        Adsorbate/Adsorbate charge-charge Real energy:              -1640567.82360744
        Adsorbate/Adsorbate charge-charge Fourier energy:             -61569.38082899
        Adsorbate/Adsorbate charge-bonddipole Real energy:                 0.00000000
        Adsorbate/Adsorbate charge-bonddipole Fourier energy:              0.00000000
        Adsorbate/Adsorbate bondipole-bonddipole Real energy:              0.00000000
        Adsorbate/Adsorbate bondipole-bonddipole Fourier energy:           0.00000000

  • 📝 For Coulombic interaction comparison, direct comparison between Real vs. Real and Fourier vs. Fourier may not agree

    • So, compare Real + Fourier in gRASPA vs. Real + Fourier in RASPA-2
    Energy gRASPA RASPA-2
    Guest-Guest Real -1652130.97 -1640567.82 ❌
    Guest-Guest Fourier -49965.27 -61569.38 ❌
    Guest-Guest Real + Fourier -1702096.24 -1702137.20 ✔