Yukawa Solids Research Articles

Orientation-dependent yield and Bauschinger effects in two-dimensional Yukawa solids

Langevin dynamics simulations of two-dimensional (2D) Yukawa solids are performed to investigate the orientation-dependent yield and Bauschinger effects in solid 2D dusty plasmas. The yield stress of 2D Yukawa solids under different conditions is determined from the corresponding stress-strain response curve, defect fraction, and deviation from the affine displacement. It is discovered that both the shear modulus and yield stress are orientation dependent, exhibiting the significant anisotropic behaviors. It is found that the dependence of the calculated atomic elastic constant on the lattice orientation completely agrees with those of the shear modulus and yield stress. It is also found that, for different initial lattice orientations, the Yukawa solid exhibits the significant regular or reverse Bauschinger effects, or even non-Bauschinger effect. Published by the American Physical Society 2024

Anelastic internal friction of dislocations in two-dimensional Yukawa solids

Anelastic internal friction of dislocations in two-dimensional Yukawa solids

Bulk moduli of two-dimensional Yukawa solids and liquids obtained from periodic compressions

Langevin dynamical simulations are performed to determine the bulk modulus in two-dimensional (2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical definition of the ratio of the internal pressure/stress to the volume strain. Under various conditions, the bulk moduli obtained agree with the previous theoretical derivations from completely different approaches. It is found that the bulk moduli of 2D Yukawa solids and liquids are almost independent of the system temperature and the external compressional frequency.

Fast particles overtaking shock front in two-dimensional Yukawa solids

High-speed particles overtaking the shock front during the propagation of compressional shocks in two-dimensional (2D) Yukawa solids are investigated using molecular dynamical simulations. When the compressional speed is lower, all particles around the shock front are almost accelerated synchronously. However, when the compressional speed is much higher, some particles penetrate the shock front to enter the preshock region. Around the shock front, it is found that the particle velocity profile at the first peak of the dispersive shock wave (DSW) is able to be described using the Gaussian distribution, so that the amplitudes of the DSW can be well characterized. As the compressional speed increases, the particle velocity corresponding to these DSW's amplitudes increase more substantially than the shock front speed. These amplitudes of the DSW are found to be able to predict the occurrence of the fast particles. Combined with the previous study of the DSW's period, it is demonstrated that the properties of the DSW are nearly not affected by the conditions of the 2D Yukawa systems, but only related to the compressional speed.

Simulations show dynamical heterogeneity at moderate shock intensities in Yukawa solids

Shocks of certain speeds allow for coexistence of solid and liquid states in 2D Yukawa solids, as demonstrated by molecular dynamics simulations.

Reply to "Comment on 'Shear modulus of two-dimensional Yukawa or dusty-plasma solids obtained from the viscoelasticity in the liquid state'".

In the preceding Comment [Khrapak and Klumov, preceding Comment, Phys. Rev. E 101, 057201 (2020)10.1103/PhysRevE.101.057201], a completely different method is used to calculate the shear modulus of two-dimensional Yukawa solids. Here the results of the shear modulus of two-dimensional Yukawa solids obtained in a previous work [Wang et al., Phys. Rev. E 99, 063206 (2019)2470-004510.1103/PhysRevE.99.063206] are compared with the results in the preceding Comment. It is found that the two empirical fits from the two methods are in extremely close agreement, supporting the consistency of these two methods.

Shear modulus of two-dimensional Yukawa or dusty-plasma solids obtained from the viscoelasticity in the liquid state.

Langevin dynamical simulations of two-dimensional (2D) Yukawa liquids are performed to investigate the shear modulus of 2D solid dusty plasmas. Using the known transverse sound speeds, we obtain a theoretical expression of the shear modulus of 2D Yukawa crystals as a function of the screening parameter κ, which can be used as the candidate of their shear modulus. The shear relaxation modulus G(t) of 2D Yukawa liquids is calculated from the shear stress autocorrelation function, consisting of the kinetic, potential, and cross portions. Due to their viscoelasticity, 2D Yukawa liquids exhibit the typical elastic property when the time duration is much less than the Maxwell relaxation time. As a result, the infinite frequency shear modulus G_{∞}, i.e., the shear relaxation modulus G(t) when t=0, of a 2D Yukawa liquid should be related to the shear modulus of the corresponding quenched 2D Yukawa solid (with the same κ value), with all particles suddenly frozen at their locations of the liquid state. It is found that the potential portion of the infinite frequency shear modulus for 2D Yukawa liquids at any temperature well agrees with the shear modulus of 2D Yukawa crystals with the same κ obtained from the transverse sound speeds. Thus, we find that the shear modulus of 2D Yukawa solids can be obtained from the motion of individual particles of the corresponding Yukawa liquids using their viscoelastic property.

Wave spectra of two-dimensional Yukawa solids and liquids in the presence of a magnetic field

Thermally excited phonon spectra of two-dimensional Yukawa solids and liquids in the presence of an external magnetic field are studied using computer simulations. Special attention is paid to the variation of wave spectra in terms of several key parameters, such as the strength of coupling, the screening parameter, and the intensity of the magnetic field. In addition, comparisons are made with several analytical theories, including random-phase approximation, quasilocalized charge approximation, and harmonic approximation, and the validity of those theories is discussed in the present context.

Collective Modes in 2-D Yukawa Solids and Liquids

We report comparative studies on collective excitations in 2-D complex plasmas, in which particles interact through the Yukawa potential, encompassing both the solid and the strongly coupled liquid states. Dispersion and polarization of the collective modes in the solid state are calculated through the lattice summations, while in the liquid state, through molecular dynamics (MD) simulations in conjunction with the theoretical quasi-localized charge approximation analysis. The latter closely emulates the dispersion, resulting from an angular averaging in the lattice. In general, however, the lattice dispersion is substantially different from that of the liquid. The MD simulations show the dramatic transformation of the anisotropic phonon dispersion of the crystal lattice near the solid-liquid transition into the isotropic liquid dispersion

Equilibrium and elastic properties of double Yukawa solids

A new method for determining the four parameters of a double Yukawa model potential is presented. Parameter values are tested by estimating the equilibrium cohesive energy, the bulk modulus and the elastic constants of cold cubic solids. An inverse method is proposed for evaluating such coefficients in the case of colloidal crystals.