Three Myths of Chemical Bonding

One sometimes reads that chemical bonding in molecules is due to spinpairing of formerly unpaired electrons. This oversimplification probably goes 

In its ground state, the paramagnetic O2 molecule exhibits an electron configuration of (IcTg) (Ic u) (2cr ) (3(7g) (ItTu) (l7r ), and the two ener- 

5) This term symbol and many others are to be found in textbooks on molecular quantum chemistry [51]. 

When this first approximate wave function is made fully self-consistent by contracting atomic orbitals ( = 1.228) which eventually fit the doubled nuclear charge, the total energy decreases by an additional amount, in harmony with the variational principle, and the kinetic energy increases strongly only at interatomic distances which are much longer than the equilibrium (bond- 

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