Abstract
We present a detailed analysis of the effects of uniaxial and biaxial strain on the frequencies of the G mode of monolayer graphene, using first principles calculations. Our results allow us to explain discrepancies in the experimentally determined values of the Gruneisen parameter. The direction and strength of the applied strain, Poisson's ratio of the substrate, and the intrinsic strain in different experimental setups turn out to be important. A reliable determination of the Gruneisen parameter is a prerequisite of strain engineering.