# Relation bewteen to different operators in different charts

Let $$\phi$$ be a coordinate system and $$\partial/\partial^{\mu}$$ and $$dx^{\mu}$$ be the associated coordiantes bases. Then in the region covered by these coordinates we can define a derivative operator $$\partial_{a}$$, such that for a tensor field $$T_{b_{1},b_{2}}$$ we take its components $$T_{\mu_{1},\mu_{2}}$$ in this coordinate basis and define be the tensor $$\partial_{a}T_{b_{1},b_{2}}$$ whose componentes in this basis are $$\partial_{\sigma}T_{\mu_{1},\mu_{2}}$$

If we choose another coordinate system $$\phi'$$ it will yield another derivative operator $$\partial_{a}'$$.

There is a way that we can relate $$\partial_{a}'$$ and $$\partial_{a}$$? I'm thinking that maybe a diffeomorphism could make the work. But I don't know how.

How about this: $$\partial_{a'}T_{b'_1b'_2}=\left(\partial_{\sigma'}T_{\mu'_1\mu'_2}\right)dx^{\sigma'}\otimes dx^{\mu_1'}\otimes dx^{\mu_2'}=\left(\partial_{\sigma'}T_{\mu'_1\mu'_2}\right)\frac{\partial x^{\sigma'}}{\partial x^\sigma}\frac{\partial x^{\mu_1'}}{\partial x^{\mu_1}}\frac{\partial x^{\mu_2'}}{\partial x^{\mu_2}}dx^{\sigma}\otimes dx^{\mu_1}\otimes dx^{\mu_2}$$
Now to deal only with components: $$\left(\partial_{\sigma'}T_{\mu'_1\mu'_2}\right)\frac{\partial x^{\sigma'}}{\partial x^\sigma}\frac{\partial x^{\mu_1'}}{\partial x^{\mu_1}}\frac{\partial x^{\mu_2'}}{\partial x^{\mu_2}} = \frac{\partial x^{\sigma'}}{\partial x^\sigma}\partial_{\sigma'}\left(T_{\mu'_1\mu'_2}\frac{\partial x^{\mu_1'}}{\partial x^{\mu_1}}\frac{\partial x^{\mu_2'}}{\partial x^{\mu_2}}\right)-\frac{\partial x^{\sigma'}}{\partial x^\sigma}T_{\mu'_1\mu'_2}\partial_{\sigma'}\left(\frac{\partial x^{\mu_1'}}{\partial x^{\mu_1}}\frac{\partial x^{\mu_2'}}{\partial x^{\mu_2}}\right)=\partial_{\sigma}T_{\mu_1\mu_2}-T_{\nu_1\nu_2}K^{\nu_1\nu_2}_{\sigma\mu_1\mu_2},$$ where: $$K^{\nu_1\nu_2}_{\sigma\mu_1\mu_2}=\frac{\partial x^{\nu_1}}{\partial x^{\mu_1'}}\frac{\partial x^{\nu_2}}{\partial x^{\mu_2'}}\partial_{\sigma}\left(\frac{\partial x^{\mu_1'}}{\partial x^\mu_1}\frac{\partial x^{\mu_2'}}{\partial x^\mu_2}\right)=\frac{\partial x^{\nu_1}}{\partial x^{\mu_1'}}\frac{\partial x^{\nu_2}}{\partial x^{\mu_2'}}\frac{\partial x^{\mu_2'}}{\partial x^\mu_2}\frac{\partial^2 x^{\mu_1'}}{\partial x^{\mu_1}\partial_\sigma}+\frac{\partial x^{\nu_1}}{\partial x^{\mu_1'}}\frac{\partial x^{\nu_2}}{\partial x^{\mu_2'}}\frac{\partial x^{\mu_1'}}{\partial x^{\mu_1}}\frac{\partial^2 x^{\mu_2'}}{\partial x^{\mu_2}\partial_\sigma}= \frac{\partial x^{\nu_1}}{\partial x^{\mu_1'}}\frac{\partial x^{\nu_2}}{\partial x^{\mu_2}}\frac{\partial^2 x^{\mu_1'}}{\partial x^{\mu_1}\partial_\sigma}+\frac{\partial x^{\nu_1}}{\partial x^{\mu_1}}\frac{\partial x^{\nu_2}}{\partial x^{\mu_2'}}\frac{\partial^2 x^{\mu_2'}}{\partial x^{\mu_2}\partial_\sigma}=\frac{\partial x^{\nu_1}}{\partial x^{\mu_1'}}\frac{\partial^2 x^{\mu_1'}}{\partial x^{\mu_1}\partial_\sigma}\delta^{\nu_2}_{\mu_2}+\frac{\partial x^{\nu_2}}{\partial x^{\mu_2'}}\frac{\partial^2 x^{\mu_2'}}{\partial x^{\mu_2}\partial_\sigma}\delta^{\nu_1}_{\mu_1}\equiv M^{\nu_1}_{\sigma\mu_1}\delta^{\nu_2}_{\mu_2}+M^{\nu_2}_{\sigma\mu_2}\delta^{\nu_1}_{\mu_1}$$ so it holds: $$\partial_{a'}T_{b'_1b'_2}=\partial_{a}T_{b_1b_2}-\left(T_{\nu_1\mu_2}M^{\nu_1}_{\sigma\mu_1}+T_{\mu_1\nu_2}M^{\nu_2}_{\sigma\mu_2}\right)dx^\sigma\otimes dx^{\mu_1}\otimes dx^{\mu_2} = \partial_{a}T_{b_1b_2} - T_{b_1c} M^c_{ab_2}-T_{cb_2} M^c_{ab_1},$$ where we defined tensor field: $$M^a_{b_1b_2}\equiv M^{\nu}_{\sigma\mu}\partial_{\nu} \otimes dx^\sigma\otimes dx^{\mu}\equiv \frac{\partial x^{\nu}}{\partial x^{\mu'}}\frac{\partial^2 x^{\mu'}}{\partial x^{\mu}\partial x^\sigma} \partial_{\nu} \otimes dx^\sigma\otimes dx^{\mu}.$$
For higher order covariant tensor fields we would get: $$\partial_{a'}T_{b'_1b'_2..b'_n} = \partial_{a}T_{b_1b_2} -T_{cb_2..b_n} M^c_{ab_1}- T_{b_1cb_3..b_n} M^c_{ab_2}-...-T_{b_1..b_{n-1}c} M^c_{ab_n}$$
Note however, that tensor field $$M$$ is indeed a tensor field - that is it transforms under change of coordinates in the correct way. However the meaning of the tensor is relating the operators $$\partial_a$$ and $$\partial_{a'}$$. The components of the tensor in different coordinate system would not relate derivative operators associated with these new coordinate system, rather the components would still relate the old derivative operators, albeit expressed in different coordinate system.