This is a bit confused because ro is used both as a parameter and a variable of integration. So first thing is to change the latter to a unique dummy variable. Then you can define
Hexp[\[Alpha]_?NumberQ, \[Beta]_?NumberQ, \[Rho]_?NumberQ, zi_?NumberQ] :=...
where ... is similar to what you have, but with Integrate replaced by NIntegrate. Also the nsqrd should be changed into a function of similar form
nsqrd[\[Alpha]_?NumberQ, \[Beta]_?NumberQ, \[Rho]_?NumberQ, zi_?NumberQ] :=...
