Thanks. The problem is that I'm not able to compute that term. I guess something like:
[γμ,γρ] Rμρ ψ
Moreover I do not know if this is the right way to solve Equation (1).
I have to compute the square of the Dirac operator, D=γaeμaDμ , in curved space time (DμΨ=∂μΨ+AabμΣab is the covariant derivative of the spinor field and Σab the Lorentz generators involving gamma matrices). Dirac equation for the massless fermion is γaeμaDμΨ=0. In particular I have to show that...