From grand-canonical density functional theory towards rational compound design

The fundamental challenge of rational compound design, ie the reverse engineering of chemical compounds with predefined specific properties, originates in the high-dimensional combinatorial nature of chemical space. Chemical space is the hyper-space of a given set of molecular observables that is spanned by the grand-canonical variables (particle densities of electrons and nuclei) which define chemical composition. A brief but rigorous description of chemical space within the molecular grand-canonical ensemble multi-component density functional theory framework will be given [1]. Numerical results will be presented for intermolecular energies as a continuous function of alchemical variations within a neutral and isoelectronic 10 proton system, including CH$_4$, NH$_3$, H$_2$O, and HF, interacting with formic acid [2]. Furthermore, engineering the Fermi level through alchemical generation of boron-nitrogen doped mutants of benzene shall be discussed [3].\newline [1] von Lilienfeld and Tuckerman {\em JCP} {\bf 125} 154104 (2006)\newline [2] von Lilienfeld and Tuckerman {\em JCTC} {\bf 3} 1083 (2007)\newline [3] Marcon et al. {\em JCP} {\bf 127} 064305 (2007)