The Study On The Structure, Thermochemistry, And Electron Affinities Of Hydrogenated Silicon Clusters

Clusters of hydrogenated silicon have attracted a lot of attention because of their applications in modern industries, especially in micro-electronics. In this paperthesis, the species ofwe studied Si5Hn (n=3–12), and Si6Hn (n=3–14) are explored and obtained the ground-state structures of ground states, electron affinities, harmonic vibrational frequencies, and dissociation energies of them and their anion are obtained by means of three with density functional theory schemesies, which are (B3LYP, BPW91, and BHLYP). The basis sets used in this work are of double-ζplus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. For Si5Hn, the fundamental frameworks of ground state structures structures of ground state of Si5Hn (n=3–8) are based on trigonal bipyramid of Si5 ground state structure that are based on five silicon atoms, and hydrogen atoms are attached to the silicon atoms and the silicon atoms are inclined to form tetra-coordinate if when n≤8., if When n is 9 or and 10, the fundamental framework of trigonal bipyramid structures are broke and the ring structures are formed, . and And if when n is 11 or and 12, the ring structures are broke and the chain and/or branch structures are formed. In the ground-state structure of Si5Hn/Si5Hn?, the silicon atoms are inclined to form tetra-coordinate. Compared with Si5Hn, the geometry of anion Si5Hn? is changed when n is 3 or and 8, and. The Si5H3? forms not only the conventional Si–H bonds but also unconventional Si–H–Si H-bridged bonds. For Si6Hn, the fundamental frameworks of ground state structures are based on the distorted bicapped tetrahedron of Si6 ground state structure when n≤8. the structures of ground state of Si6Hn (n=3–8) are distorted bicapped tetrahedron that are based on six silicon atoms, ifWhen n > 9 8, the silicon atoms are possibly inclined to form various ring, chain, and/or branch structures for bonding hydrogen atoms with tetra-coordinate bonds. Compared with neutral Si6Hn, the mainly changes of geometries of their anion is obviously rearrangement of silicon atoms Wwhen n is =7, 8, 10 or and 13, geometry of them is obviously changed.. The reason for it is that the framework of silicon is reordered in the internal molecule. Similarly Si5Hn/Si5Hn?, the silicon atoms of Si6Hn/Si6Hn? are inclined to form tetra-coordinate. For the bond lengths of both clusters, generally order of the three methods is BPW91>B3LYP>BHLYP. For the electron affinities, the B3LYP and the BPW91 predict the most reliable results and t, The BHLYP predict the worst reliable resultsones. For the dissociation energies, The BHLYP predicts the maxima values, and the BPW91 predicts the minima values.