  Models of diffusion in white dwarfs universally rely on the coefficients
calculated by Paquette et al. (1986). We present new calculations of diffusion
coefficients based on an advanced microscopic theory of dense plasmas and a
numerical simulation approach that intrinsically accounts for multiple
collisions. Our method is validated against a state-of-the-art method and we
present results for the diffusion of carbon ions in a helium plasma.
