Nabh <sub> 4 </ Sub> First-principles Calculation And Srod Molecular Electronic Structure Study

This paper is consist of two parts:calculations of the structural, electronic and elastic properties of NaBH4 using GGA and LDA of exchange-correlation function, comparison of the two approximation for predicting the physical properties, electronic structure research on SrOD molecular.The first chapter is consist of hydrogen, hydrogen storage principle and the situation of the research. As a kind of clean, abundant, high efficient energy carrier, hydrogen has attracted wide concern. In the process of the using of hydrogen, hydrogen storage is the most important part and has yet solved successfully. Methods for hydrogen storage are mainly:(1) gaseous storage, (2) liquid storage, (3) adsorption of nanomaterials, (4) metal hydrides, (5) complex hydride. The traditional gas, liquid storage are not ideal because of the unsafety, difficulties in hydrogen storage and transportation. While solid hydrogen storage materials have been widely studied as one kind of safe, convenient for transportation, high density of hydrogen method.The second chapter mainly introduces the approximate density function:Local density approximation (LDA)and Generalized gradient approximation(GGA). Because LDA is based on the ideal uniform electron gas model,electron density of real atoms and molecules in the system is far from uniform. In order to improve the calculation accuracy further, we need to consider the inhomogeneity of electron density. So we got GGA.In the third chapter, we calculated the lattice, electronic and elastic properties of NaBH4 based on density function theory with GGA and LDA of exchange-correlation function. Our results indicate that GGA is more favorable than LDA for predicting physical properties, such as lattice constants, band gaps and elastic properties.In the fourth chapter, we showed the methods we used to optimize SrOD molecular ground-state bond length using Gaussian code. Furthermore, Molcas program based on the MCSCF using reference state Caspt2 (the second perturbation of active space) are used to calculate the bond length, relative ground-state energy and the potential energy curve (PEC) of SrOD molecules. In conclusions, we found a new state of SrOD, which is not reported by experiments yet and calculated its bond length and PEC. We prove the configuration of C2(?) is nonlinear structure and confirm the conjecture of the experiment.