To whom it may concern
I want to simulate a polymer (Polybutylene terephthalate) with class 2 force filed (PCFF). It is a common structure.
I built it in material studio and convert its files (.mdf & .car) to LAMMPS data fie by msi2lmp.
Now, I have problem with the Eaa in the data file. I think the data file is incorrect in this section.
In accordance to User Guide>> Improper Styles >> improper_style class2 command
Teta 1: Teta (ijk), Teta 2: Teta (ijl), Teta3: Teta (kjl)
X 1: dihedral (ijkl) and is the angle between the plane of ijk & jkl (the plane included teta 1 & Teta 3) correspond to M1 (all the thing is OK, X1 & M1 are Brought in the same level).
X 2: dihedral (kjli) and is the angle between the plane of kjl & jli (the plane included teta 3 & Teta 2), this is correspond to M3 (all the thing is correct, but X2 & M3 are Brought in same level which is confusing).
X 3: dihedral (ljik) and is the angle between the plane of lji & jik (the plane included teta 2 & Teta 1), this is correspond to M2 (all the thing is correct, but X3 & M2 are Brought in same level which confusing).
It is the structure of data file which built by msi2lmp
AngleAngle Coeffs
1 0.0000 0.0000 0.0000 117.9400 118.9000 117.9400
2 0.0000 0.0000 0.0000 125.5320 120.7970 108.4400
3 0.0000 0.0000 5.9863 118.9000 116.0640 116.0640
4 0.2738 0.2738 -0.4825 107.6600 110.7700 110.7700
5 0.0000 0.0000 0.0000 107.6600 107.6880 107.6880
6 0.0000 0.0000 0.0000 110.7700 107.4100 107.6880
7 -1.3199 0.1184 -1.3199 110.7700 112.6700 110.7700
8 0.2738 0.2738 -0.4825 107.6600 110.7700 110.7700
9 -0.3157 -0.3157 -0.3157 107.6600 107.6600 107.6600
10 0.2738 0.2738 -0.4825 107.6600 110.7700 110.7700
11 -1.3199 0.1184 -1.3199 110.7700 112.6700 110.7700
I check all the parameters in this section, all rows. The problem is:
The 7th and 11th rows are similar to each other, and in accordance to User Guide it should be as below,
M1 M2 M3 Teta1 Teta2 Teta3
7 0.1184 -1.3199 -1.3199 110.7700 112.6700 110.7700 (In accordance to user guide)
But in data file
7 -1.3199 0.1184 -1.3199 110.7700 112.6700 110.7700 (data file)
M1 should be correspond to the angle between the plane of ijk & jkl (teta 1 & Teta 3),
M2 should be correspond to the angle between the plane of lji & jik (teta 1 & Teta 2),
M3 should be correspond to the angle between the plane of kjl & jli (teta 2 & Teta 3).
In 4th row:
110.7700= Teta 1= c c h
112.6700 = Teta 2= c c c
110.7700= Teta 3= c c h,
M1 should be the dihedral between the planes included Teta 3, 1 (c c h c)= 0.1184 (from PCFF file) but in data file it is -1.3199 and it seems be incorrect.
M2 should be the dihedral between the planes included Teta 1, 2 (c c c h)= -1.3199 (from PCFF file) but in data file it is 0.1184 and it seems be incorrect.
M3 should be the dihedral between the planes included Teta 2, 3(c c c h)= -1.3199 (from PCFF file) and it is correct.
I check all the rows and in these rows the LAMMPS data file is different with User guide, please check it and tell me what I can do.
The MSI files (.car, .mdf ) and data file attach to this email.
I look forward hearing from you.
Sincerely,
maliheh
P1-pcff.car (22.6 KB)
P1-pcff.data (100 KB)
P1-pcff.mdf (24.6 KB)