The problem of the existence and stability of various types of self-trapped (ST) states (polarons) in 1-d molecular systems has been analysed within the framework of the general theory of self-trapping phenomena. An interpolation method is applied to cover the whole range of system parameters. In the system phase diagram we specify the areas where different ST states may exist. The role of the soliton mechanism in the energy and charge transport in biological systems has been critically revised on the basis of these results
