Short-range order in Valenta model of thin films

The present paper deals with the Valenta model for magnetic thin films extended to the entropy construction in its pair representation. The problem of the thin films theory is old, but the Valenta model introduced fifty years ago seems to be still an effective approach requiring however, some modifications. The most important one is connected with the improvement of the entropy construction in the self-consistent way when the correlations are taken into account. The idea is introduced in the present paper and discussed in detail.