Structure And Physical Properties Of ASbF₃Cl（A=alkali Metal） Materials And ScLi_n Clusters

Nonlinear optical materials are widely used in modern manufacturing,laser medical treatment,communication and other fields.Therefore,many scholars are devoted to the research and development of new nonlinear optical materials with higher performance.Alkali metal cations are easier to obtain nonlinear optical materials with short cutoff edges because of the absence of d-d and f-f transitions,whether the alkali metals contribute to the optical properties of the material?The introduction of units containing stereochemical active lone pairs(such as cationic primitives containing d¹⁰ electrons,lone pair electrons,etc.)is an effective way to obtain nonlinear optical materials.Is there a positive correlation between lone pair electrons and optical properties?Are the effects of different halogens on the optical properties of materials different?And whether the structural prediction can be realized by theoretical calculation.In view of the above problems,the author has carried out three different works and drawn some conclusions:Firstly,the electronic structure and birefringence of post-transition metal halides ASb F₃Cl（A=K,Rb,Cs）and Sb X₃（X=Cl,Br,I）are calculated by using first-principles software.There is an asymmetric distribution of lone pair electrons around antimony cations.The modified model of lone pair electrons in metal oxides is also applicable to metal halides after transition.The order of the energy difference between the s state of antimony and the p state of halogen is Sb-Cl<Sb-Br<Sb-I.The stereotactic activity of lone pair electrons is determined by the energy difference between the s state of the cation and the p state of the halogen.For binary post-transition metal halides,the birefringence increases from Cl to I,and the p-orbital of the cation plays a major role in the birefringence.Then,for the high-throughput screening test,we try to use the simple binary cluster ScLi_n（n=2-13）containing alkali metals to screen the CALYPSO structure,and the stable geometric structure,electronic and magnetic properties of the clusters were studied.Except for ScLi₂,all ScLi_n（n=2-13）clusters tend to three-dimensional structure.Among these ScLi_n clusters,ScLi₁₂ and ScLi₁₃ have cage structure,and ScLi₁₂ clusters have icosahedral structure.After combining the results of average binding energy,second-order energy difference and fragmentation energy,ScLi₁₂ clusters are considered to be magnetic superatoms.The ScLi₁₂ cluster has the largest spin magnetic moment（3μB）.The magnetic behavior of these clusters can be explained by the jellium model and its molecular orbital is 1S²1P⁶1D_α⁵D_β².In the ScLi₁₂ cluster,the charge is transferred from the Li atom to the Sc atom,so that the contribution of the Li atom and the Sc atom to the total magnetic moment is almost equal.Finally,the structure of crystal materials is screened based on Calypso program.Through the comparison of the results of different algorithms,we find that the artificial bee colony algorithm can get more reasonable crystal structure data.The properties of the selected structure are calculated and compared with those of the experimental structure,which also verifies this conclusion.For different types of crystal materials,we will use different methods to predict and screen the structure.