Investigations On The Symmetry Energy Of Nuclear Matter By IQMD

Nuclear matter generally refers to infinite nuclear matter,it is an important subject in nuclear physics.The study of nuclear matter helps us to understand the basic properties of nuclear matter,the interaction between nucleons,the structure and evolution of neutron stars and other celestial bodies.Existing theories have a good description of isospin symmetric nuclear matter,and because of isospin asymmetric nuclear matter often corresponds to extreme conditions,the study is relatively rare.Nuclear matter's EOS(Equation of State)is the relationship between the mean nucleon energy,density,temperature and isospin asymmetry.The EOS is commonly used to describe basic properties of nuclear matter.EOS of nuclear matter is closely related to the binding energy which has a great influence on nuclear stability.Mean nucleon energy can be expanded according to asymmetries.Symmetry energy is an important reason for nucleus has the same number of nucleons but different stability.There are important reasons for differences in stability.The QMD(Quantum Molecular Dynamics)model is often used to simulate heavy-ion transport process in the low and medium energy region.The IQMD(Isospin-dependent Quantum Molecular Dynamics)model adds isospin effects in QMD model,so effects made by different asymmetries can be better described by IQMD.Main work of this study is to use IQMD model to simulate nuclear matter of different isospin asymmetries,densities and temperature,obtain and extract information in EOS,and finally make a brief comparison and discussion with the results of other studies.The first chapter mainly introduces the research background and the significance.The second chapter introduces the concepts of QMD model,including the basic concept of MD(molecular dynamics)model,the mean field used in the IQMD model and the simulation process.In the last part of this paper,symmetry energy was briefly discussed.The third chapter mainly introduces the results of the study.Using IQMD model,EOS and symmetry energy of isospin asymmetric nucleus matter can be studied.Nuclear matter under different densities,isospin asymmetries and temperatures was simulated.Symmetry energies were extracted from EOS under different conditions and compared with CMD(classical molecular dynamics)model using the same method.The results show that both models can reproduce the experimental results of symmetry energy at low density,but IQMD is more suitable than CMD for nuclear matter above the saturation density.It suggests that IQMD may be a good model for studying the properties of infinite nuclear matter.Finally,the paper makes a brief summary.