Chaotic instantons in periodically perturbed double-well system
  Kicked double-well system is investigated both analytically and numerically. Phenomenological formula for ground quasienergy splitting is obtained using resonances overlap criterion in the framework of chaotic instanton approach. Results of numerical calculations of quasienergy spectrum are in good agreement with the phenomenological formula. 
V.I. Kuvshinov, A.V. Kuzmin and V.A. Piatrou