Variational approximations in discrete nonlinear Schr\"odinger equations   with next-nearest-neighbor couplings
  Solitons of a discrete nonlinear Schr\"{o}dinger equation which includes the next-nearest-neighbor interactions are studied by means of a variational approximation and numerical computations. A large family of multi-humped solutions, including those with a nontrivial phase structure which are a feature particular to the next-nearest-neighbor interaction model, are accurately predicted by the variational approximation. Bifurcations linking solutions with the trivial and nontrivial phase structures are also captured remarkably well, including a prediction of critical parameter values. 
C. Chong, R. Carretero-Gonz\'alez, B.A. Malomed and P.G. Kevrekidis
nlin.PS