The momentum for the Hamiltonian system in Eq. (1) can be expressed as H=1/2 ∫_(-∞)^∞▒〖Ω^2 dφ), here H represents the momentum, 𝛺 denotes the electric field potential. The sufficient condition for soliton stability is ∂H/∂Ω >0, but here I have Ω=(8τρ_1^2 v^2)/(3kσ_0^2 ε(16r^2 v^2 - 8rs^2 v + s^4 ) ), now what I should I do for differentiating with respect to Ω or with respect to t ?