Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.Th...Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.The calculated results show that the C72(D6d) which satisfies the isolated-pentagon rule is the most stable structure among the three isomers of C72,while the potential minimum Vmin(r) inside the sphere of C72(#10611) is the biggest one among the three isomers of C72 considered.So C72(#10611) is easier to accept electrons from the scandium atoms than the other two isomers.Upon endohedral doping by Sc2,the(#10611) isomer is more highly stabilized thermodynamically and kinetically.展开更多
Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In...Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.展开更多
国际标准化组织(International Orga-nization for Standization)简称为ISO。ISO下设181个技术委员会(Technical Commit-tees,简称TC),负责协调组织各个行业的国际标准的制订工作。TC之下设立分委员会(Sub-committees,简称SC),负责制订...国际标准化组织(International Orga-nization for Standization)简称为ISO。ISO下设181个技术委员会(Technical Commit-tees,简称TC),负责协调组织各个行业的国际标准的制订工作。TC之下设立分委员会(Sub-committees,简称SC),负责制订各专业的国际标准。SC的下面又根据工作项目设立工作组(working groups,简称WG)。ISO的第46技术委员会-TC46,负责协调组织情报、展开更多
文摘Density functional theory(DFT) calculations on three fullerene isomers of C72 were carried out at the B3LYP/6-31G* level.The optimized configurations and the electrostatic potential distributions have been obtained.The calculated results show that the C72(D6d) which satisfies the isolated-pentagon rule is the most stable structure among the three isomers of C72,while the potential minimum Vmin(r) inside the sphere of C72(#10611) is the biggest one among the three isomers of C72 considered.So C72(#10611) is easier to accept electrons from the scandium atoms than the other two isomers.Upon endohedral doping by Sc2,the(#10611) isomer is more highly stabilized thermodynamically and kinetically.
基金This work was supported by the National Key Basic Research Program of China （No.2013CB921800）, the National Natural Science Foundation of China （No.11374291, No.11311120047, No.11274299, No.11447197, and No.11204292）, the Fundamen- tal Research Funds for the Central Universities （No.WK20304200）, the Anhui Provincial Natural Science Foundation （No.1508085QA09）. The numerical calculations have been partially done on the super- computing system in the Supercomputing Center of University of Science and Technology of China.
文摘Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3＋ centers in Ca3Sc2Si3O12 by considering the effects of the charge com- pensations related to N3-, Sc3＋, Mn2＋, Mg2＋, and Na＋. Firstly, the local structures around Ce3＋ are optimized by using density functional theory calculations with supercell model. The 4f→5d transition energies of Ce3＋ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3＋-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3＋ substituting Si4＋. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.
