Dear users,
I still can not solve the problem of including two potentials using into one input script. I searched a lot to sort out the problem but I can not find the solution. This time the error is : ERROR: Incorrect args for pair coefficients (…/pair_reaxc.cpp:288)
Last command: pair_coeff * * reax/c ffield.reax.cho C C C C C C H H H H H H H H H H H H O O O O O O
My system has zinc oxide and glucose. I want to use field.reax.cho for glucose and ffield.reax.ZnOH for ZnO.
My input script is:
REAX potential for ZnOH2 system
…
units real
atom_style charge
read_data out_vmd.data
pair_style hybrid reax/c NULL
pair_coeff * * reax/c ffield.reax.cho C C C C C C H H H H H H H &
H H H H H O O O O O O
pair_coeff * * reax/c ffield.reax.ZnOH O Zn
neighbor 2 bin
neigh_modify every 2 delay 10 check yes page 100000
dump 1 all xyz 10 file2.xyz
#dump_modify 1 element C C C C C C H H H H H H H H H H H H O O O O O O
fix 2 all qeq/reax 1 0.0 10.0 1e-6 reax/c
minimize 1.0e-10 1.0e-10 10000 10000
fix 1 all nve
fix 2 all qeq/reax 1 0.0 10.0 1e-6 reax/c
fix 3 all temp/berendsen 500.0 500.0 100.0
reset_timestep 0
timestep 0.25
run 3000
print “All done!”
And the masses in data file are arranged in the following way:
Masses
1 12.011000 # C1
2 12.011000 # C2
3 12.011000 # C3
4 12.011000 # C4
5 12.011000 # C5
6 12.011000 # C6
7 1.008000 # H1
8 1.008000 # H1o
9 1.008000 # H2
10 1.008000 # H2o
11 1.008000 # H3
12 1.008000 # H3o
13 1.008000 # H4
14 1.008000 # H4o
15 1.008000 # H5
16 1.008000 # H6R
17 1.008000 # H6S
18 1.008000 # H6o
19 15.999000 # O1h
20 15.999000 # O2h
21 15.999000 # O3h
22 15.999000 # O4h
23 15.999000 # O6h
24 15.999000 # OR
25 15.999000 # OZ
26 65.38 # ZN
So please help me.
With regards
Sasthi
There are multiple problems here.
- you are not following the required syntax for pair_coeff statements. there have to be as many entries as following as you have total atom types.
- your use of pair style hybrid is incorrect for using pair style reax/c twice
- pair style reax/c does not (yet) support multiple instances in a hybrid style
- if you have only one reax/c pair style instance, there can be only one pair_coeff statement with one force field file, thus your second entry would wipe out the first
- you cannot mix and match difference reaxff force field files like this. you need a specific parameterization for your system. reaxff is not like quantum chemistry, where you only need to specify the elements; you need a specific parameterization.
- your force field file for the glucose likely like a parameterization for combustion. is that what you want?
- you have no cross interactions for the two reax/c parts.
in short, even if you figure out all the syntax issues, you will still get bogus results. there is no way, that this system with this approach can be modeled in a meaningful way.
axel
Dear Axel thank you for your reply. I have tried all possibilities like, reax/c once, twice, hybrid. All the time I got error. And one thing I cannot understand why you are saying this model gives bogus results. It is written that fffield.reax.ZnOH developed for ZnO and ffield.reax.cho for biomolecules. So I could not get your point. Your suggestion is always helpful to me. Please suggest something on this.
Regards
Sasthi
.
Dear Axel thank you for your reply. I have tried all possibilities like, reax/c once, twice, hybrid. All the time I got error. And one thing I cannot understand why you are saying this model gives bogus results.
It is written that fffield.reax.ZnOH developed for ZnO and ffield.reax.cho for biomolecules.
written where? the ffield.reax.cho bundled with LAMMPS is parameterized for combustion studies.
So I could not get your point. Your suggestion is always helpful to me. Please suggest something on this.
all i have to say, is in my previous e-mail. if you don’t understand it, then perhaps you should try a different project.
axel.