| Abstract
| - Second-order Møller−Plesset (MP2) calculations (using the approximate resolution of the identity, RI-MP2)in the TZVPP basis are performed to study the interaction of molecular hydrogen with the aromatic systemsC6H5X (X = H, F, OH, NH2, CH3, and CN), C10H8 (naphthalene and azulene), C14H10 (anthracene), C24H12(coronene), p-C6H4(COOH)2 (terephthalic acid), and p-C6H4(COOLi)2 (dilithium terephthalate). Variousadsorption positions are studied for C6H5F. The most favorable configuration places H2 above the aromaticplane with its axis pointing toward the middle of the ring. The electronic (van der Waals) interaction energyfor the differently substituted benzenes correlates with the ability of the substituents to enrich the aromaticsystem electronically. The largest interaction energy (among the singly substituted benzenes) is found foraniline (4.5 kJ mol-1). Enlarging the aromatic system increases the interaction energy; the value for coroneneamounts to 5.4 kJ mol-1. Extending the basis set and including terms linear in the interelectronic distancesincreases the interaction energy by about 1 kJ mol-1 relative to that of the TZVPP basis, whereas the inclusionof higher excitations by coupled-cluster calculations (including all single and double excitations with aperturbative estimate of triples, CCSD(T)) decreases the interaction energy by about the same amount.
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