  The molecular dissociation energy has often been explained and discussed in
terms of singlet bonds, formed by bounded pairs of valence electrons. In this
work we use a highly correlated resonating valence bond ansatz, providing a
consistent paradigm for the chemical bond, where spin fluctuations are shown to
play a crucial role. Spin fluctuations are known to be important in magnetic
systems and correspond to the zero point motion of the spin waves emerging from
a magnetic broken symmetry state. Recently, in order to explain the excitation
spectrum of the carbon dimer, an unusual quadruple bond has been proposed.
Within our ansatz, a satisfactory description of the carbon dimer is determined
by the magnetic interaction of two Carbon atoms with antiferromagnetically
ordered S = 1 magnetic moments. This is a first step that, thanks to the highly
scalable and efficient quantum Monte Carlo technique, may open the way for
understanding challenging complex systems containing atoms with large spins
(e.g. transition metals).
