Messages

I am trying to make benzene molecules using the OPLS 1990 JACS paper, which is simply LJ+Coulomb and has no bonds, angles, or torsion.
If I do the following, I get "Error in CBMC growing scheme.. No atoms can be grown, check the connectivity of your molecule." How do I solve this error?
I also changed the end of the force_field_mixing_rules file from "Lorentz-Berthelot" to "Jorgensen"
I would like to avoid implementing bonds and angles in the topology if possible because I believe the calculations will be faster.

-------------------------------------------------------------------------------------
# critical constants: Temperature [T], Pressure [Pa], and Acentric factor [-]
562.05
4894000.0
0.2092
# Number Of Atoms
12
# Number of groups
1
# benzene-group
rigid
# number of atoms
12
# atomic positions
0 C_benz  0.00000000    0.00000000    0.00000000
1 C_benz  1.39200000    0.00000000    0.00000000
2 C_benz  2.08800000    1.20550736    0.00000000
3 C_benz  1.39200051    2.41101443   -0.00119599
4 C_benz  0.00000000    2.41101459   -0.00167420
5 C_benz -0.69600000    1.20550717   -0.00068061
6 H_benz -0.54000000   -0.93530733    0.00044182
7 H_benz  1.93200000   -0.93530654    0.00129125
8 H_benz  3.16799982    1.20550747    0.00062273
9 H_benz  1.93200056    3.34632183   -0.00125416
10 H_benz -0.53999901    3.34632180   -0.00260212
11 H_benz -1.77600000    1.20550708   -0.00085731
# Chiral centers Bond  BondDipoles Bend  UrayBradley InvBend  Torsion Imp. Torsion Bond/Bond Stretch/Bend Bend/Bend Bend/Torsion IntraVDW IntraCoulomb
               0   0            0    0            0       0        0            0         0            0         0            0        0            0

Thank you for your explanation.
I think I should take a step back and start from the top.

I want to calculate the vapor pressure of certain molecules using MC.

1. Is GEMC the most effective way to meet my objective? If not, what is a better way to obtain vapor pressure using RASPA?

2. After further studying the  Non-Basic/Gibbs_CO2 example output, I found that the pressure has not been calculated. I am assuming that if I can get the pressure for both vapor and liquid systems, this will be the saturation pressure at the given temperature and calculated system volumes for each system. Please let me know if I am misunderstanding something.

3. How do I get RASPA to compute pressure for GEMC?

4. If I am simulating a molecule, where the critical properties are not known, can I use RASPA to estimate the critical properties? (The previous studies do not show data points close to the critical point.)

Hi.

I am interested in getting pure component vapor pressures and am thinking of using GEMC. I have read the manual about CO2 and checked the Non-Basic/Gibbs_CO2 example and have a few questions.

1. What output property should I use to determine if I am using enough cycles and molecules?

2. The adsorbate/adsorbate energy shows a lot of variance. How much fluctuation is generally acceptable to ensure the simulation is in equilibrium?

3. What is a good rule of thumb in changing input parameters to get stable results?
(ex.  increase no. of cycles > increase molecules > increase swaps)

Thanks in advance!