A detailed theoretical formalism for the calculation of energy levels and eigenfunctions of molecules with a large amplitude coordinate in the presence of a strong laser pulse is developed based on a discrete variable representation to setup the Hamiltonian matrix. This approach is applied to nonrigid biphenyl-like molecules displaying a large amplitude motion corresponding to respective rotations of their two groups. The eigenvalues and eigenvectors obtained in several limiting cases of the hindering potential can be symmetry labeled and provide us with useful insights into the feasibility of torsional alignment. The present results support the rotation-induced breakdown of torsional alignment, under adiabatic following, previously described by Coudert, Pacios, and Ortigoso [Phys. Rev. Lett. 107, 113004 (2011)].

• Received 20 November 2012

DOI:https://doi.org/10.1103/PhysRevA.87.043403