“…Problem (1.2) has been studied extensively in recent years. See [1,2,5,7,8,9,10,11,13,16,17,18,21,23,24,26,30,43,44] for backgrounds and references. The case V (y) ≡ 1 or a(y) = 0 corresponds to the Allen-Cahn equation [6] ǫ 2 ∆u + u(1 − u 2 ) = 0 in Ω, ∂u ∂ν = 0 on ∂Ω,…”