Density Functional Theory Study For Tungsten Clusters And Its Adsorption Of H₂

The structures of W_nH₂?n=1-6? clusters,W_nH₂?n=7-12? clusters and W_n^0,±?n=7-12? clusters are computed using Density Functional Theory?DFT? in the Gaussian and Dmol3 package. Search the lowest energy structure as the ground-state structures, and based on them some relative physicochemical properties was calculated. Results are as follows:?1? H₂ molecules adsorbed on the W_n clusters are systematically investigated by using density functional theory at the B3LYP/LANL2DZ level.The result indicates that The chemisorption of H atoms on W_n clusters belongs to dissociative adsorption, and the lowest energy structures of W_nH₂ are generated with H atoms being adsorbed on the lowest energy structure of W_n clusters, and the lowest energy structures of W_n clusters are not changed by adsorbing H atoms. From the analysis of infrared spectroscopy, we found that the highest peaks of W_nH₂?n=1-6? clusters have relatively high vibration intensity which are mostly concentrate upon 350cm-1 and 200 cm-1.?2?The structure and magnetic properties of W_nH₂?n=7-12? clusters have been systematically investigated using density functional theory?DFT? within the generalized gradient approximation?GGA?. The result indicates that the ground state structures of W_nH₂ clusters are generated when H₂ dissociative adsorbed on the atop site of W_n clusters. W₈H₂ and W₁₀H₂ clusters are found to be more stable than other clusters. The adsorption abilities of W_n clusters are related to W-H bond length,adsorption energy and the charge transfer between H and W clusters as well as the electronic density of state. From the analysis of infrared spectroscopy, we found that the highest peaks of W_nH₂?n=7-12? clusters have relatively high vibration intensity which are mostly concentrate upon500cm-1 and 1800 cm-1.?3? The structure and magnetic properties of W_n^±?n=7-12? clusters have been systematically investigated using density functional theory?DFT? within the generalized gradient approximation?GGA?. The result indicates that the ground state structures of W_n^±?n=7-12? clusters are similar with the ground state structures of W_n?n=7-12? clusters. The stability analysis shows that anion clusters are more stable than neutral clusters, and cation clusters have lowest stability. W₈ cluster is magic cluster. The magnetic properties analysis shows that there are many unpaired electrons around the atoms of W₁₀ and W₁₁ clusters. From the analysis of infrared spectroscopy, we found that W₁₀ and W₁₁ clusters have different infrared spectroscopy and vibrational mode.