Shannon Entropy In Configuration Space For Ni-like Isoelectronic Sequence

Entropy was first proposed by Clausius,aiming to describe the direction of spontaneous thermodynamic process in the form of the law of increasing entropy of thermodynamics of isolated systems.Subsequently,Boltzmann connected the macroscopic properties of the system with the microscopic state and proposed Boltzmann entropy.Then,Shannon introduced the concept of entropy into information theory.He explained the transmission of information from the perspective of quantity and put forward the concept of information quantity.Information entropy,as a measure of the uncertainty of random events,lays the foundation of modern information science.Later,with the continuous development of the concept of information entropy,Shannon entropy has been applied in many disciplinesIn this paper,the discrete Shannon entropy is introduced from the mathematical properties of the multiconfiguration wavefunctions,and then it is used to describe the level information of atomic states contained in the multiconfiguration Dirac-Hartree-Fock wavefunctions of Ni-like isoelectronic sequences.The first chapter mainly introduces the development and application of Shannon entropy in recent years,especially the application background of Shannon entropy in atomic physics.In the second chapter,the multiconfiguration Driac-Hartree-Fock method is systematically described,and some important modifications in the multi-configuration method are briefly introduced.Based on the mathematical properties of the multi-configuration wave function,the concept of discrete Shannon entropy is introduced.In Chapter 3,the Shannon entropies are shown for the ground and single excited states,along with the Ni-like isoelectronic sequence.Then,the relationship between the sudden change of Shannon entropy,information exchange,eigenlevel anticrossing,and strong configuration interaction is discussed based on the calculated energy levels,then we found that there is an interesting connection between these four concepts along with the nuclear charge Z,which is helpful to conveniently locate the position of eigenlevel anticrossings and information exchanging and understand them from the point of view of information,besides the traditional physical concepts.Especially,it is concluded that in a given configuration space eigenlevel anticrossing is a sufficient and necessary condition for the sudden change of Shannon entropy,which is also a sufficient condition for information exchange.Based on the study of Shannon entropy properties in different configuration spaces,we discuss the Shannon entropy of the ground and single excited states in the LS coupled-basis configuration space for Ni-like isoelectronic sequence in the Chapter 4.Finally,some concluding remarks and outlook are summarized in the Chapter 5.