[Pw_forum] measuring covalent vs. ionic nature of Li bonding in LiC6

[Yaser Rehem]

Dear Pwscf Users-

Can anyone offer advice on how best to measure the nature of Li  
bonding in LiC6?  I've used projwfc.x to calculat the pDOS of the  
valence Li electron in a relaxed LiC6 structure, and I find the  
results surprising.  If I use a gga ps, I find that the valence Li  
electron in LiC6 has an approximately 55% overlap with it's free  
valence states, and an approximately 69% overlap if I use an lda ps  
with a semi-core.   Many studies show the charge transfer from Li to C  
in LiC6 to be almost complete--i.e., the Li is essentially fully  
ionized--hence my surprise at the pDOS results.

Can anyone offer alternate method(s) by which I can assess the  
relative covalent vs. ionic nature of Li bonding in this structure?

Thank you,

-Yaser Rehem
Rehem Research & Consulting
(a.k.a. Yaser working in his basement :-)