Pair potential for TiO2

Dear Lammps user
I want to do MD simulation on TiO2 for radiation damage. I have searched literature review and found, scientist use Pedone potential and Matsui_Akaogi potential. I have written a pair potential but not sure is it correct or not. Below I have given the file pair style using LAMMPS code
Matsui_Akoagi potential:

------------------Define Interatomic Potential -----------------

pair_style buck/coul/long 2.5
pair_coeff 1 1 31120 0.154 5.250
pair_coeff 1 2 16958 0.194 12.590
pair_coeff 2 2 11783 0.234 30.220
kspace_style ewald 1.0e-4

Pedone Potential:

------------------Define Interatomic Potential -----------------

pair_style hybrid/overlay morse 15.0 lj/cut 15.0 coul/long 15.0
pair_coeff * * coul/long
pair_coeff 1 2 morse 0.024235 2.254703 2.708943
pair_coeff 2 2 morse 0.042395 1.379316 3.618701
pair_coeff 1 2 lj/cut 1.0 1.0
pair_coeff 2 2 lj/cut 1.0 22.0
kspace_style ewald 1.0e-8

In both cases, 1 is Titanium and 2 is Oxygen. Can anybody help me with it? I have another question, I have used these potential but all the cases,
I got error
ERROR: Must use ‘kspace_modify gewald’ for uncharged system (src/KSPACE/ewald.cpp:163)

I have written this pair style based on LAMMPS archives. I have another question
Why they did not use Ti-Ti interaction?
Can I use meam potential for TiO2 radiation damage which I already found in this website. " "

Please note, that is up to you to verify the correctness of your input by reproducing results from the publications that you are taking the parameters from. This mailing lists is not an input validation service. More importantly, you cannot write in a paper, that some dude on a mailing list tolds you, that your input was correct.

The lj/cut parameters look very wrong. The error is due to not having assigned any (partial) charges to atoms (which are likely needed for your compound).