Erratum to: Geodesic Deviation Equation in f(R) Gravity

Abstract: In the context of metric $f(R)$ gravity, the Geodesic Deviation Equation (GDE) was first studied in arXiv:1010.5279v3, giving a general expression and studying a particular case, the FLRW universe. In the paper arXiv:1312.2022v1 a similar analysis was made. However, there is a discrepancy in the expressions for the null vector field case due to an algebraic error in our original paper. Here, we make explicit the contribution of the different operators in the GDE, and we correct our previous results.