Variational Approximations of Bifurcations of Asymmetric Solitons in Cubic-Quintic Nonlinear Schroedinger Lattices

Using a variational approximation we study discrete solitons of a nonlinear Schroedinger lattice with a cubic-quintic nonlinearity. Using an ansatz with six parameters we are able to approximate bifurcations of asymmetric solutions connecting site-centered and bond-centered solutions and resulting in the exchange of their stability. We show that the numerically exact and variational approximations are quite close for solitons of small powers.