  Potassium is introduced into the crystalline herringbone structure of
pentacene searching for a compound showing metallic electronic transport
properties and, hopefully, superconductivity at small enough temperatures.
Several possible structures for stoichiometric KPentacene (1:1), K2Pentacene
(2:1) and K3Pentacene (3:1) compounds are theoretically investigated. Detailed
densities of states for all of them are presented. As a more prominent result,
a new monoclinic structure has been stabilized for the potassium richer
material that could correspond to the recently synthesized superconducting
phase of K3Pentacene. Although energetically unfavorable, it is the only
metallic candidate found to date.
