Dear lammps users,
My research object is Pd/Al2O3 interface system and I use “fix qeq/slater” command to perform the charge equilibration on Al2O3. Pd is described via EAM potential and its charge is set to be 0. When I run lammps simulation the following ERROR message appears:
Invalid param file for fix qeq/slater (Zeta value is 0.0)
Could you please tell me how to deal with this problem? Or is there a better method to perform the charge equilibration on partial atoms of the system?
Thank you in advance.
Best wishes,
Lily
Dear lammps users,
My research object is Pd/Al2O3 interface system and I use “fix qeq/slater” command to perform the charge equilibration on Al2O3. Pd is described via EAM potential and its charge is set to be 0. When I run lammps simulation the following ERROR message appears:
Invalid param file for fix qeq/slater (Zeta value is 0.0)
Could you please tell me how to deal with this problem? Or is there a better method to perform the charge equilibration on partial atoms of the system?
two things:
- you must not use "impossible" parameters, even if they are not
supposed to be used.
- you should be able to restrict to which group of atoms fix qeq/XXX
is applied by choosing a suitable fix group.
axel.
Thank you! I have tried to apply fix qeq/slater to only the Al2O3 atoms as follows:
（ Type1: Al
Type2: O
Type3: Pd
……….）
Compute charge1 type1 property/atom q
Compute q1 type1 reduce ave c_charge1
Compute charge2 type2 property/atom q
Compute q2 type2 reduce ave c_charge2
Variable qcat equal 2.8
Variable qani equal -${qcat}*count(type1)/count(type2)
Set group type1 charge ${qcat}
Set group type2 charge ${qani}
Variable qsum equal count(type1)*c_q1+count(type2)*c_q2
Pair_style hybrid/overlay ….
Pair_coeff * * coul/streitz AlO.streitz Al O NULL
Pair_coeff * * eam/alloy AlO.eam.alloy Al O NULL
Pair_coeff 3 3 eam….
……
Fix 1 ceramic qeq/slater 1 12.0 1.0e-6 100 coul/streitz
Minimize 1e-25 1e-25 5000 10000
Thank you! I have tried to apply fix qeq/slater to only the Al2O3 atoms as follows:
you cannot use the "coul/streitz" option in your case to automatically
use the QEQ parameters from the coul/streitz pair style. you must use
a separate parameter file for fix qeq (format is described in the
docs) which has entries for all atom types, but you can put any valid
parameters in there for Pd atoms, because you will not use them, but
valid they must be regardless. by that token, a value of 0.0 for zeta
is illegal.
axel.