Assessment of the Performance of B2PLYP-D for Describing Intramolecular π-π and σ-π Interactions

E-mail: ykhan@kbsi.re.krReceived September 15, 2011, Accepted September 28, 2011Intramolecular π-π and σ-π interactions are omnipresent for numerous energetic and structural phenomena innature, and the exact description of these nonbonding interactions plays an important role in the accurateprediction of the three-dimensional structures for numerous interesting molecular systems such as proteinfolding and polymer shaping. We have selected two prototype molecular systems for benchmarkingcalculations of intramolecular π-π and σ-π interactions. Accurately describing conformational energy of suchsystems requires highly elaborate but very expensive ab initio methods such as coupled cluster singles, doubles,and (triples) (CCSD(T)). Our calculations reveal a double hybrid density functional incorporating dispersioncorrection (B2PLYP-D) that agrees excellently with the CCSD(T) results, indicating that B2PLYP-D can serveas a practical method of choice. Key Words : Conformation analysis, Density functional theory, Dispersion interaction, π-π interaction, σ-πinteractionIntroductionElectronic structure calculations in organic, biomolecular,and nano-based material systems have widely used tradi-tional density-functional theory (DFT).