Table 3.

Energy results from the calculation of the mechanism involving a tetrahedral intermediate (mechanism A, Figure 2).

Structure	Calculated energy (Hartree)	Added small molecules	Adjusted energy (Hartree)	Relative energy (kJ/mol)
1	−13.6629	urea and water	− 15.9521	0
2	−14.8816	2 water	−15.9376	38.0
3	−14.3532	3 water	−15.9373	38.9
4	−14.3315	3 water and one H+	−15.8951	150
5	−14.3150	3 water	−15.8991	139
6	−13.6828	ammonia and 3 water	−15.8981	142
7	−13.6629	ammonia and carbamic acid	−15.9505	−33.9
8	−13.6629	2 ammonia and carbon dioxide	−15.9451	18.3