CCL:G: Difficulties with Hirshfeld Population Analysis

["Adil R Zhugralin" <zhugrali+*+bc.edu>]

 Sent to CCL by: "Adil R Zhugralin" [zhugrali:_:bc.edu]
 Dear all,
 I have been trying to calculate Hirshfeld charges (from HPA) in Gaussian03 with
 iop(6/79=1), and I've been getting unrealistically large charges even in a
 neutral molecule (Sum of Hirshfeld charges=-79.225986). Both cation and anion
 HPA gave me ******** for the "Sum of Hirshfeld charges". I need HPA to
 estimate fukui indices/atomic softness indices through finite difference
 approximation for an organometallic complex, containing Mo(VI) atom (opt and
 freq were done as a separate job at B3PW91/6-31+G(d,p) and SDD on Mo).
 I wonder if HPA does not handle ECPs well or are there any other ways for me to
 get HPA working? Different level of theory or charge method? I did try to use
 Mulliken, Lowdin, charges, but I get negative f- functions for atoms of interest
 (gross atomic charges of the cation are higher than those of the neutral
 molecule). Is Voronoi Deformation Density (VDD) method available in Gaussian?
 All responses would be appreciated, thanks in advance,
 Adil R. Zhugralin
 Boston College, Department of Chemistry