Role Of Disorder In The Vibrational Properties Of Amorphous Solids And Glass-forming Ability

Solid materials are composed of crystals and amorphous solids.Crystals are well researched because of their periodic lattice structure.It's quite interesting that amor-phous solids,not crystals,are closely related to our daily life.In the form of another solids,amorphous solids are called disordered solids.They have various forms and un-usual characters.In the past few decades,the problem related to their characters are still bothering condensed matter physics community,but it is still a long way to estab-lish a perfect,self-consistent theory.Recently,more and more people try to understand amorphous solids from the transition between crystals and amorphous solids.These re-searches includes the role of the disorders played in the transition between crystals and amorphous solids;what are the effects on amorphous by introducing complex disor-dered structures;almost all materials can be transited to amorphous solids under certain appropriate condition,what is the role of disorder in producing amorphous solids.In the introduction(Chapter 1),we first briefly introduce soft matter,its prominent characteristics and the research status of amorphous materials,and then focus on the dynamic characteristics,thermodynamic characteristics and some important theoretical models of the glass transition.Then starting from the Jamming phase diagram,in fi-nite-range-repulsive ideal model,we further discuss the behavioral characteristics of Jamming transition and Jammed system.In Chapter 2,we briefly introduce the calculation of normal mode and the charac-terization,intrinsic normal mode analysis is used to help for understanding important visual point of view of amorphous solid.In addition to this,the boundary conditions used in the simulation and methods for determining stability of disordered solids are introduced.In Chapter 3,we study the role of different types of disorder in determining the vibrational properties of disordered systems.By separately introducing four types of disorder to a two-dimensional perfect triangular lattice,we obtain findings that enhance our understanding of the origin of the boson peak and the relationship between the boson peak and the transverse Ioffe-Regel limit.Otherwise,By comparing combinations of two types of disorder to jammed solids,we conclude that the local coordination number fluctuation is important to determine the low-frequency vibration of marginally jammed solids,whereas lattice site position disorder affects mainly the intermediate-and high-frequency vibration.Our results suggest that both local coordination number and posi-tional disorder are necessary for the argument to be hold,which is actually the case for most disordered solids such as marginally jammed solids and structural glasses.In chapter 4,we explore the connection between the glass-forming ability of nonequlib-rium glass-formers and the equilibrium melting temperature.Due to the distinction in particle size or stiffness in the two common models of glass-formers(i.e.soft-core model and hard-core model),the two components in the mixture effectively feel dif-ferent melting temperatures,leading to a melting temperature gap.Firstly,we find the direct link between the glass-forming ability and the melting temperature gap.Secondly,by varying the particle size,stiffness,and composition over a wide range of pressures,we establish a comprehensive picture for the glass-forming ability.Meanwhile,our study reveals the pressure and interaction dependence of the glass-forming ability of model glass-formers,and suggests strategies to optimize the glass-forming ability via the manipulation of particle interactions.In Chapter 5,we summarize this paper and discuss future work.