The Density Functional Theory Study Of Phosphorus And Alkaline Earth Metal Be, Mg, Ca Doped Phosphorus Clusters

In this paper, geometry structure and electronic properties of pure phosphorus clusters and phosphorus-doped alkaline earth metal Be, Mg, Ca clusters are studied based on the density functional theory of quantum chemical methods first principles. The primary coverage is as follows:First, we not only introduced the development, research content, the basic concepts of clusters of scientific and the significance of clusters studying briefly, but also summarized the main methods and achievements of cluster study in recent years. Then we introduced the research question and development trend of bivalent mental and phosphorus concerned in this paper and got a summary and discussion of the scientific significance of the study. Based on this, the elementary knowledge of the density functional theory and Gaussian03 and so on software were introduced.Second, possible geometry configuration of pure phosphorus P_n (n = 1-12) were calculated in the use of the first principle at the B3LYP\6-311G level. The structures of the clusters with the lowest energy were obtained. Partial data given in the paper were analyzed. Take alkali earth metal Mg as an example, geometry structure and electronic properties of phosphorus-doped alkaline earth metal were studied emphatically. The computation situation is as follows: geometry structure, stability and electronic properties of Mg_nP_m were carried on a more detailed study on the calculation in the use of density functional theory at the B3LYP\6-311G level. We found in the research, Clusters form five rings and four rings structure easily with n+m≥4. The second-order difference energy and energy gap could be calculated on the structure of lowest energy indicated that the stability of MgP₄, MgP₆, Mg₂P₂ and Mg₂P₄ are higher relatively. While in the further analysis of electronic configuration, it is found that the access of charge of P atom depended on the distance between the P and Mg atom.Finally, the ground state structures of M_nP_m(n=1～2,m=1～10)(M=Be,Mg,Ca)clusters were obtained with the structure optimization and frequency analysis at the B3LYP/6-311G level based on the density function theory. The calculated results indicate that the stabilities of M_nP_m clusters with m+n=5,6 that adopt the cone structures are higher than the same size with other structures while the four or five ring are the ground state structures for the MnPm clusters with m+n>6. When m=2 the MP_m(m=1-10) clusters simultaneously obtains the same local maximum value and the magic numbers of Be₂P_m(m=1-10) clusters exhibit the odd-even oscillation on the fragmentation energy and the second order difference. In comparison to Mg, Ca atoms, Be atom prefer to interact to P atoms of which its stability is higher. The MP₂ clusters exhibit the stronger activity of IR and Raman at the higher frequency size, and the main peak of the IR spectra also appear at the higher frequency size of the Mg₂P₂ and Ca₂P₂ clusters which is opposite to the main peak of Raman spectra through the investigation of the IR and Raman spectra for the magic numbers.