Abstract:

The effect of including vs. excluding diffuse functions while calculating numerous parameters of PAH anions by various calculation methods is discussed. The omission of diffuse functions. appears to have a negligible effect while calculating geometry parameters or total energy; thus, acceptable results may be obtained without them. The conclusions for charge density appear to be the same; however, limited results make an unambiguous claim unachievable. Calculating H-1- and C-13-NMR shifts undoubtedly requires the use of these functions.