# Finite difference time domain and dynamic permittivity

Since the permittivity of any material is usually complex function of temperature, frequency, density, etc. I was wondering if it is possible to use a dynamic permittivity which changes as a function of time using the fdtd method. This would also enable to simulate moving objects. Any hints, keywords, etc.?

• Yes, you can use the method with a coefficient that changes with time. – nicoguaro Mar 11 '18 at 15:54

• linear dispersion: dielectric permittivity ($\epsilon$) and magnetic permeability ($\mu$) of the material vary with frequency $\omega$: $\epsilon(\omega)$, $\mu(\omega)$
• nonlinearity dispersion: $\epsilon(\omega,E,H)$, $\mu(\omega,E,H)$, dependence on the field intensity