Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session TT02: V: Computational Methods for Statistical Mechanics - Advances and Applications |
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Sponsoring Units: DCOMP Chair: Jingyi Zhuang, Columbia University Room: Virtual Room 2 |
Tuesday, March 21, 2023 3:30PM - 3:42PM |
TT02.00001: Conductance distribution in a random matrix model Kazi A Alam, Khandker A Muttalib Numerical solutions of the tight-binding Anderson model show that the distribution of conductance P(g) in a disordered conductor near the Anderson metal-insulator transition in three dimensions (3D) is very broad and highly asymmetric. Surprisingly, the distribution is also similarly broad and asymmetric near the smooth metal-insulator crossover in a quasi-one dimensional (Q1D) disordered conductor. There is no analytical framework currently available that can obtain P(g) directly, or study the subtle differences in the distributions between 3D and Q1D. We propose a random matrix model that allows us to study the full distribution in detail in both cases. |
Tuesday, March 21, 2023 3:42PM - 3:54PM |
TT02.00002: Wang-Landau Sampling of Lattice Multiblock Copolymers Robert F Bull, Alfred C Farris, David P Landau Synthetic multiblock copolymers are an interesting class of polymeric chains and have emerged as promising materials to mimic the function of complex biomolecules [1, 2]. In this work, we use Wang-Landau sampling [3] to study sequences of multiblock A_{n}B_{n} copolymers in the rigid lattice. We first compare the thermodynamic and structural properties of sequences studied in the continuum to study the differences that arise during the collapse process [4]. We then focus on the structural transitions that occur at temperatures below the coil-to-globule transition in the lattice. Moreover, by studying additional sequences, we detail the relationship between block length, number of blocks, and thus overall polymer length with respect to said structural transitions. Lastly, we observe how the formation and shape of a ground state core of the more strongly interacting monomer type affects the procession of structural changes that occurs as temperature increases. |
Tuesday, March 21, 2023 3:54PM - 4:06PM |
TT02.00003: Monte Carlo Simulations of the Three-dimensional Heisenberg model with Dzyaloshinskii-Moriya interactions Joao A Plascak, Gabriel d Silva, David P Landau The three-dimensional Heisenberg model on a simple cubic lattice with Dzyaloshinskii-Moriya (DM) interactions^{1} between nearest-neighbor along all directions has been studied using Monte Carlo simulations. The Metropolis algorithm, together with single histogram techniques and finite-size-scaling analysis, have been used to obtain the thermodynamic behavior of the system in the thermodynamic limit. Instead of using fluctuating boundary conditions^{2} , in order to take into account the incommensurability that results from the extra vectorial energetic term, we have determined, a priori, the shift angle at the boundary as a function of the DM interaction. This method has proved to decrease the simulation time significantly. We found that the ordered state has a spiral configuration for all values of non-zero DM interaction with the system undergoing a conventional second-order phase transition. The phase diagram, in the temperature versus DM interaction, has been obtained. |
Tuesday, March 21, 2023 4:06PM - 4:18PM Author not Attending |
TT02.00004: Random batch Quasi-Ewald method for the simulations of charged particles under dielectric confinement Xuanzhao Gao Quasi-2D charged systems are attracting much attention because of their potential in future nanodevices. |
Tuesday, March 21, 2023 4:18PM - 4:30PM |
TT02.00005: Monte Carlo Simulation of Zirconium-Based Metal-Organic Framework Adsorption Matthew Browe Metal-organic frameworks (MOFs) are a class of materials that has been heavily studied for gas adsorption, among numerous other applications. Zirconium-based MOFs such UiO-66 and MOF-808, in particular, are of high interest due to their stability under a wide range of synthetic and environmental conditions. Understanding adsorption on a pore-type basis is important for being able to elucidate design strategies for improving these materials. Additionally, these materials can deviate greatly from their pristine (perfect) structures, including induction of missing-linker defects, termination chemistry of those defects, and presence of residual solvent (consisting of dimethylformamide and water). Grand Canonical Monte Carlo (GCMC) simulations using RASPA and force fields for nitrogen, water, and dimethyl formamide adsorption on these zirconium-based MOFs have been performed to understand the differences in the nitrogen adsorption isotherm of these materials upon induction of these structural modifications. Trends and differences in the adsorption on a pore type basis will be discussed. |
Tuesday, March 21, 2023 4:30PM - 4:42PM |
TT02.00006: A Computational Illustration of Born-von Karman Periodic Boundary Conditions in Dynamics of 1D and 2D Lattices. Jeet Shannigrahi, Pragati Ashdhir, Vishnu Vijayan The concept of periodic boundary conditions (PBCs) is immensely significant in treating an ideal lattice of infinite extent as a finite lattice. An explicit usage of PBCs is often found missing in undergraduate texts on analytical treatment of lattice dynamics. The aim of the present work is to cover this gap by illustrating the application of Born-von Karman PBCs in lattice dynamical calculations using a computational approach. The equations of motion are set up for a linear diatomic lattice with a basis, using the nearest neighbour approximation. The solution is obtained by implementing fourth order Runge-Kutta algorithm in python. Fast Fourier Transform (FFT) technique is then used to obtain the phonon frequency spectrum corresponding to the computed solutions. Similar computations are extended to obtain the phonon spectrum for a square lattice under the second nearest neighbour approximation. The target group of the present work are the students and educators at the undergraduate level. |
Tuesday, March 21, 2023 4:42PM - 4:54PM |
TT02.00007: Numerical Evidence on spin-Coulomb drag and spin mass in the uniform electron gas Zhiyi Li, Pengcheng Hou, Youjin Deng, Kun Chen Coulomb interaction between spin up and down electrons causes an intrinsic source of friction for spin currents in an electron liquid. This phenomenon, known as the spin-Coulomb-drag (SCD) effect, has not yet been experimentally confirmed in the three dimensions. We investigate this problem in the context of a three-dimensional uniform electron gas with the recently developed variational diagrammatic Monte Carlo method. We calculate the momentum and frequency resolved spin-antisymmetric exchange-correlation kernel with a high precision. We find strong numerical evidence of the SCD effect and establish the relevant fundamental parameters (such as the effective spin mass). Our numerical results could motivate new SCD experiments in the three-dimensional quantum materials. |
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