|
|
Spin polarization effect for Tc2 molecule
Yan Shi-Ying (阎世英), Zhu Zheng-He (朱正和)
Chinese Physics, 2004, 13 (12):
2053-2057.
DOI: 10.1088/1009-1963/13/12/013
Density functional method (DFT) (B3p86) of Gaussian98 has been used to optimize the structure of the Tc$_2$ molecule. The result shows that the ground state for Tc$_2$ molecule is an 11-multiple state and its electronic configuration is $^{11}$Σ$_{\rm g}^-$, which shows the spin polarization effect of Tc$_2$ molecule of a transition metal element for the first time. 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, that the ground state for Tc$_2$ molecule is an 11-multiple state is indicative of the spin polarization effect of Tc$_2$ molecule of a transition metal element: that is, there exist 10 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Tc$_2$ molecule is minimized. It can be concluded that the effect of parallel spin of the Tc$_2$ 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 $^{11}$Σ$_{\rm g}^-$ and other states of Tc$_2$ molecule are derived. Dissociation energy $D_{\rm e}$ for the ground state of $T_{\rm c2}$ molecule is 2.266eV, equilibrium bond length $R_{\rm e}$ is 0.2841nm, vibration frequency $\omega_{\rm e}$ is 178.52cm$^{-1}$. Its force constants $f_2$, $f_3$, and $f_4$ are 0.9200aJ$\cdot$nm$^{-2}$, --3.5700aJ$\cdot$nm$^{-3}$, 11.2748aJ$\cdot$nm$^{-4}$ respectively. The other spectroscopic data for the ground state of Tc$_2$ molecule $\omega_{\rm e}\chi_{\rm e}$, $B_{\rm e}$, $\alpha_{\rm e}$ are 0.5523cm$^{-1}$, 0.0426cm$^{-1}$, $1.6331\times10^{-4}$cm$^{-1}$ respectively.
|
