  Here we investigate whether well-known DFT-GGA errors in predicting the
chemisorption energy ($E_{\rm chem}$) of CO on transition metal surfaces
manifest in analogous NO chemisorption systems. To verify the occurrence of
DFT-GGA overestimation of the back-donation mechanism in NO Chemisorption, we
use electronic structure analysis to show that the partially filled molecular
NO 2$\pi^{*}$ orbital rehybridizes with the transition metal $d$-band to form
new bonding and anti-bonding states. We relate the back-donation charge
transfer associated with chemisorption to the promotion of an electron from the
5$\sigma$ orbital to the 2$\pi^{*}$ orbital in the gas-phase NO
G$^{2}\Sigma^{-}\leftarrow \rm{X}^{2}\Pi$ excitation. We establish linear
relationships between $E_{\rm chem}$ and $\Delta E_{\rm G\leftarrow X}$ and go
on to formulate an $E_{\rm chem}$ correction scheme in the style of Mason {\it
et al.}, {[Physical Review B {\bf 69}, 161401(R)]}. We apply the NO $E_{\rm
chem}$ correction method to the (111) surfaces of Pt, Pd, Rh, and Ir, with NO
chemisorption modeled at a coverage of 0.25 ML. We note that both the slope of
$E_{\rm chem}$ {\it vs.} $\Delta E_{\rm G\leftarrow X}$ and the dipole moment
depend strongly on adsorption site for each metal, and we use this fact to
construct an approximate correction scheme which we go on to test using
NO/Pt(100) chemisorption.
