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Influences of dispersion and long-range corrections on molecular structures of three types of lithium phthalocyanine dimer



We report here the results from theoretical calculations of the potential energy curves for three dimers of lithium phthalocyanine (LiPc) using nine types of functionals: the M06-2x, M06L, B97D, ωB97, ωB97X, ωB97XD, CAM-B3LYP, LC-ωPBE, and LC-BLYP. The results were discussed in comparison with those obtained for the dimers of magnesium phthalocyanine (MgPc). The dispersive and long-range interactions were considered in part by using these functionals. The mechanism whereby the dispersive and long-range interactions affect the geometric structures of the LiPc and MgPc dimers is discussed. The calculated results provide insight into the computational methods for both open- and closed-shell metal phthalocyanine (MPc) dimers: Although it is difficult for the CAM-B3LYP, LC-ωPBE, and LC-BLYP functionals only with the long-range corrections to evaluate weak dispersion interactions appropriately, the M06-families, ωB97-families, and B97D functionals can estimate a weak dispersion interaction well in both open- and closed-shell MPc dimers. However, the results should be used with caution against overestimation of the relative stabilities for the results of functionals considering despersion correction. © 2012 Wiley Periodicals, Inc.