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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., Comment: Please, write an e-mail to jav@icmm.csic.es if you need some of the structural data mentioned in the manuscript (.cif files)

The geometrical and electronic structure of tripotassium doped phenanthrene, \ce{K3C14H10}, have been studied by first-principles density functional theory. The main effect of potassium doping is to inject charge in the narrow phenanthrene conduction band, rendering the system metallic. The Fermi surface for the experimental X-rays unit cell is composed of two sheets with marked one and two dimensional character respectively., Comment: 4 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1106.0377

The geometrical and electronic structure of potassium doped phenanthrene, \ce{K3C14H10}, have been studied by first-principles density functional theory. The main effect of potassium doping is to inject charge in the narrow phenanthrene conduction band, rendering the system metallic. The Fermi surface for the experimental X-rays structure is composed of two sheets with marked one and two dimensional character respectively.

The crystal structure of potassium doped picene with an exact stoichiometry (K3C22H14, K3picene from here onwards) has been theoretically determined within Density Functional Theory allowing complete variational freedom of the crystal structure parameters and the molecular atomic positions. A modified herringbone lattice is obtained in which potassium atoms are intercalated between two paired picene molecules displaying the two possible orientations in the crystal.Along the c-axis, organic molecules alternate with chains formed by three potassium atoms. The electronic structureof the doped material resembles pristine picene, except that now the bottom of the conduction band is occupied by six electrons coming from the ionized K atoms (six per unit cell). Wavefunctions remain based mainly on picene molecular orbitals getting their dispersion from intralayer edge to face CH/pi bonding, while eigenenergies have been modified by the change in the electrostatic potential. The small dispersion along the c-axis is assigned to small H-H overlap. From the calculated electronic density of states we expect metallic behavior for potassium doped picene., Comment: Published version: 8 twocolumn pages, 7 color figures, 2 structural .cif files included