Melting of Amorphous Silica

Hello pooja.

want to simulate amorphous silica for which I will be melting and quenching the amorphous phase with the BKS potential.

Before simulating you have to equilibrate the system.
After equilibration the system has to be heated to 5000 K (Check order parameters rdf, autocorrelation…)
Check what happens to the density and other thermodynamic outputs and also observe the box dimensions.
From your lammps input script I see that you are in the equilibration stage and you have not yet started the quenching process.

I performed simulation with NVE ensemble and then also tested with fix NVT and fix NPT both. But for all the cases the temperature of the system was increasing.

I suspect this may be due to bad geometry.
Please minimize the system before you start the equilibration to eliminate close contacts. Then use fix nve, nvt with langevin and switch to npt.

Good luck