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A. Sharma et al.
the nucleonic level and shed light on the collective behavior of a nucleus in terms of
n/p ratio in a nucleus. The term isospin means a pair of identical particles (nucleons),
i.e., either neutrons or protons in nuclear matter when their electric charges aren’t
taken into consideration. In nuclear physics, isospin degree of freedom makes its
presence in various phenomenon (like Multifragmentation, Collective Flow, Nuclear
Stopping, etc.) and thus attracts the attention of the nuclear physics community.
Experimental studies involving neutron-rich nuclei have set an excellent platform
to investigate the isospin dependence in the dynamics of heavy-ion collisions at
intermediate energies. It has also opened up a new field that helps in extracting the
information regarding the equation of state of asymmetric nuclear matter, a topic of
current debate. A large number of studies have been reported in the literature where
authors have investigated the role of the isospin degree of freedom in heavy-ion collisions at intermediate energies [7, 9–12]. The prime aim of such studies is to probe
the properties of nuclear matter in the region between symmetric nuclear matter and
pure neutron matter. This information also helps to understand various Astrophysics
phenomena such as Supernova, Neutron Stars, etc.
It is worth mentioning that now large information has been collected on fragmentation but the major problem is that all experimental measurements are done when
the matter is cold. Therefore, it is obvious that to understand the phenomenon of
fragmentation, there is a need for authentic theoretical models/approaches. Broadly,
theoretical models/approaches can be divided into statistical and dynamical models/approaches. The dynamical models are of two types 1. Isospin-independent like
VUU, QMD, AMD, etc. [8, 13–19] 2. Isospin-dependent like ImQMD, IBUU,
IQMD, etc. [20–22]. The isospin-dependent Quantum Molecular Dynamics (IQMD)
Model [22] is the improved version of the QMD [8] model with isospin degree of
freedom incorporated in it. With the inclusion of isospin degree of freedom, the
IQMD model has symmetry potential, isospin dependence nucleon–nucleon cross
section and improved Pauli blocking. Also, it is worth mentioning that dynamics
of symmetric and asymmetric reactions is quite different [7, 12, 23]. Therefore, it
would be interesting to probe isospin effects using IQMD model on the dynamics of
asymmetric heavy-ion collisions at intermediate energies. This chapter is organized
as follows: in Sect. 4.2, we will give a brief introduction to the formalism used to carry
out calculations. Then, in Sect. 4.3, we will review our recently published results for
multifragmention. Finally, Sect. 4.4 is devoted to a summary of the chapter.
4.2 Isospin-Dependent Quantum Molecular Dynamics
(IQMD) Model
The IQMD model [22] treats different charge states of nucleons, deltas, and pions
explicitly, as inherited from the Vlasov–Uehling–Uhlenbeck (VUU) model [24].
The IQMD model has been used successfully for the analysis of a large number of
A. Sharma et al.
the nucleonic level and shed light on the collective behavior of a nucleus in terms of
n/p ratio in a nucleus. The term isospin means a pair of identical particles (nucleons),
i.e., either neutrons or protons in nuclear matter when their electric charges aren’t
taken into consideration. In nuclear physics, isospin degree of freedom makes its
presence in various phenomenon (like Multifragmentation, Collective Flow, Nuclear
Stopping, etc.) and thus attracts the attention of the nuclear physics community.
Experimental studies involving neutron-rich nuclei have set an excellent platform
to investigate the isospin dependence in the dynamics of heavy-ion collisions at
intermediate energies. It has also opened up a new field that helps in extracting the
information regarding the equation of state of asymmetric nuclear matter, a topic of
current debate. A large number of studies have been reported in the literature where
authors have investigated the role of the isospin degree of freedom in heavy-ion collisions at intermediate energies [7, 9–12]. The prime aim of such studies is to probe
the properties of nuclear matter in the region between symmetric nuclear matter and
pure neutron matter. This information also helps to understand various Astrophysics
phenomena such as Supernova, Neutron Stars, etc.
It is worth mentioning that now large information has been collected on fragmentation but the major problem is that all experimental measurements are done when
the matter is cold. Therefore, it is obvious that to understand the phenomenon of
fragmentation, there is a need for authentic theoretical models/approaches. Broadly,
theoretical models/approaches can be divided into statistical and dynamical models/approaches. The dynamical models are of two types 1. Isospin-independent like
VUU, QMD, AMD, etc. [8, 13–19] 2. Isospin-dependent like ImQMD, IBUU,
IQMD, etc. [20–22]. The isospin-dependent Quantum Molecular Dynamics (IQMD)
Model [22] is the improved version of the QMD [8] model with isospin degree of
freedom incorporated in it. With the inclusion of isospin degree of freedom, the
IQMD model has symmetry potential, isospin dependence nucleon–nucleon cross
section and improved Pauli blocking. Also, it is worth mentioning that dynamics
of symmetric and asymmetric reactions is quite different [7, 12, 23]. Therefore, it
would be interesting to probe isospin effects using IQMD model on the dynamics of
asymmetric heavy-ion collisions at intermediate energies. This chapter is organized
as follows: in Sect. 4.2, we will give a brief introduction to the formalism used to carry
out calculations. Then, in Sect. 4.3, we will review our recently published results for
multifragmention. Finally, Sect. 4.4 is devoted to a summary of the chapter.
4.2 Isospin-Dependent Quantum Molecular Dynamics
(IQMD) Model
The IQMD model [22] treats different charge states of nucleons, deltas, and pions
explicitly, as inherited from the Vlasov–Uehling–Uhlenbeck (VUU) model [24].
The IQMD model has been used successfully for the analysis of a large number of