Gravitational frequency-shift and deflection of light by quintessence

In this paper we investigate the gravitational frequency-shift and deflection of light in the Schwarzschild black hole space-time surrounded by quintessence. With the analytical and numerical methods, we find that the gravitational frequency-shift of light in the Schwarzschild black hole space-time surrounded by the quintessence increases as the values of the normalization factor c increases, but the gravitational frequency-shift of light decreases with the quintessential state parameter \omega_\rm q increasing. We also calculate the deflection of light by quintessence and find that the deflection rate decreases as the values of the quintessential parameters c and \omega_\rm q increase.