The density functional theory method (DFT) (b3p86) of Gaussian 03 has been used to optimize the structure of the Mn2 molecule.The result shows that the ground state of the Mn2 molecule is an 11-multiple state,indicating a spin polarization effect in the Mn2 molecule,a transition metal element molecule.Meanwhile,we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions of higher-energy states.So the ground state for Mn2 molecule being of an 11-multiple state is the indicative of spin polarization effect of the Mn2 molecule among those in the transition metal elements:that is,there are 10 parallel spin electrons in a Mn2 molecule.The number of non-conjugated electrons is the greatest.These electrons occupy different spacious orbitals so that the energy of the Mn2 molecule is minimized.It can be concluded that the effect of parallel spin in the Mn2 molecule is larger than the effect of the conjugated molecule,which is obviously related to the effect of electron d delocalization.In addition,the Murrell-Sorbie potential functions with the parameters for the ground state and other states of the Mn2 molecule are derived.The dissociation energy De for the ground state of the Mn2 molecule is 1.4477eV,equilibrium bond length Re is 0.2506 nm,vibration frequency ωe is 211.51 cm-1.Its force constants,f2,f3,and f4 are 0.7240 aJ·nm-2,-3.35574 aJ·nm-3,11.4813 aJ·nm-4 respectively. The other spectroscopic data for the ground state of the Mn2 molecule ωeχe,Be,αe are 1.5301 cm-1,0.0978 cm-1,7.7825×10-4 cm-1 respectively.