Is this available in pytorch?

I was working on the SIR pandemic model with neural network.The input of the model is the daily increasing cases and outputs the parameters alpha and beta(size:N->2N)
so I take the outputs into the SIR model and compute the prediction of the daily increasing cases.
And finally,the loss fuction is MSELoss(input,prediction of the daily increasing cases)
But it turns out to not train at all,here’s my code,how can I fix it?Thanks a lot.
By the way,I was doing it on jupyter notebook.

those are my code and reading file: