TABLE 5. Results of the Natural Bond Order Analysis (B3LYP/6-311++G**).

TABLE 5.1. Urea

Bond orbital	Population	Atom	Natural charge
π(C-O)	1.654	O	−0.647
σ (C-N1)	1.822	C	+0.784
σ (C-N2)	1.822	N	−0.841
LP(N1)	1.828
LP(N2)	1.828
LP1(O)	1.978
LP2(O)	1.853
Donor Orbital	Acceptor Orbital	E(2), kcal/mol	E(i) – E(j), a. u.	Fij, a. u.
LP(N1)	π* (C-O)	40.53	0.32	0.106
LP(N2)	π* (C-O)	40.53	0.32	0.106
LP2(O)	σ* (C-N1)	24.20	0.67	0.115
LP2(O)	σ* (C-N2)	24.20	0.67	0.115