The success of Density Functional Theory(DFT)is partly due to that of simple approximations,such as the Local Density Approximation(LDA),which uses results of a model,the homogeneous electron gas,to simulate exchange-...The success of Density Functional Theory(DFT)is partly due to that of simple approximations,such as the Local Density Approximation(LDA),which uses results of a model,the homogeneous electron gas,to simulate exchange-correlation effects in real materials.We turn this intuitive approximation into a general and in principle exact theory by introducing the concept of a connector:a prescription how to use results of a model system in order to simulate a given quantity in a real system.In this framework,the LDA can be understood as one particular approximation for a connector that is designed to link the exchange-correlation potentials in the real material to that of the model.Formulating the in principle exact connector equations allows us to go beyond the LDA in a systematic way.Moreover,connector theory is not bound to DFT,and it suggests approximations also for other functionals and other observables.We explain why this very general approach is indeed a convenient starting point for approximations.We illustrate our purposes with simple but pertinent examples.展开更多
基金This research was supported by a Marie Curie FP7 Integration Grant within the 7th European Union Framework Programme,the European Research Council under the EU FP7 framework program(ERC grant No.320971)the Austrian science Fund FWF under Project No.J 3855-N27.
文摘The success of Density Functional Theory(DFT)is partly due to that of simple approximations,such as the Local Density Approximation(LDA),which uses results of a model,the homogeneous electron gas,to simulate exchange-correlation effects in real materials.We turn this intuitive approximation into a general and in principle exact theory by introducing the concept of a connector:a prescription how to use results of a model system in order to simulate a given quantity in a real system.In this framework,the LDA can be understood as one particular approximation for a connector that is designed to link the exchange-correlation potentials in the real material to that of the model.Formulating the in principle exact connector equations allows us to go beyond the LDA in a systematic way.Moreover,connector theory is not bound to DFT,and it suggests approximations also for other functionals and other observables.We explain why this very general approach is indeed a convenient starting point for approximations.We illustrate our purposes with simple but pertinent examples.
