Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session M58: Plyler Prize, Jankunas AwardPrize/Award
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Sponsoring Units: DCP Chair: Albert Stolow, Univ of Ottawa Room: Mile High Ballroom 3B |
Wednesday, March 4, 2020 11:15AM - 11:39AM |
M58.00001: Understanding Electron Correlation via Computational Quantum Chemistry Joonho Lee, Martin P Head-Gordon Computational quantum chemistry has become a valuable tool to understand complicated physics arising from the correlated motion of electrons in molecules and materials. In quantum chemistry, we categorize electron correlation mainly into two classes: weak and strong correlation. Weakly correlated electrons can be efficiently handled by perturbation theory (PT). On the other hand, such PT methods completely break down for systems with strong correlation, which then usually requires far more computationally demanding approaches. My thesis addresses multiple aspects of the challenges posed by these two classes of correlation. In this talk, I will present three representative examples from my thesis. First, I will discuss the development of a PT method that can distinguish weak and strong correlation [1]. Secondly, I will present a Kohn-Sham density functional theory approach that can handle some strongly correlated systems by breaking time-reversal symmetry [2]. Lastly, I will discuss the development of a method that can efficiently treat strong spin correlation between electrons and its application to a single molecular magnet [3]. |
Wednesday, March 4, 2020 11:39AM - 12:03PM |
M58.00002: Light bipolarons stabilized by strong Peierls electron-vibration coupling: A new hope for high-temperature superconductivity [Justin Jankanas Doctoral Dissertation Award] John Sous Striking emergent phenomena crucial to understanding the dynamical behavior of complex many-body molecular systems manifest thanks to coupling to vibrational excitations, including vibrationally stabilized Rydberg molecules and vibration-mediated binding of electron pairs in superconductors. Here, I show that the Peierls coupling, describing the modulation of electron motion due to vibrations, stabilizes light yet strongly bound bipolarons that survive strong Coulomb repulsion. I show that these properties result from the specific form of the vibration-mediated interaction, which is of 'pair-hopping' instead of regular density-density type. Furthermore, I provide evidence suggestive of a regime of bipolaronic phases stable against phase separation. These light bipolarons could well undergo Bose-Einstein condensation at high temperatures, opening a door to a new mechanism for high-temperature superconductivity. This may help resolve open questions regarding superconductivity in vibrationally coupled systems. |
Wednesday, March 4, 2020 12:03PM - 12:27PM |
M58.00003: Quantum control of cold molecular collisions using Stark-induced adiabatic Raman passage William Perreault One of the most fundamental goals in chemical physics is to understand the interaction forces that bind matter together at the quantum level. Molecular scattering experiments are the foremost tool with which to interrogate these forces, but the amount of detailed information that can be extracted from these experiments is limited by how precisely the input and output quantum states are defined. This talk will present the progress made by our group towards completely quantum state controlled scattering experiments. We first developed the Stark-induced adiabatic Raman passage technique to prepare specific internal molecular quantum states in simple molecules, and then used this technique to study the rotationally inelastic scattering of state-prepared molecules at very low collision energies. Under these conditions, nearly complete control over the quantum states was achieved, allowing us to experimentally derive insight into the dynamics of molecular scattering. This work shows the power of complete control over the input quantum states and complete measurement of the output quantum states to understand the molecular-scale world experimentally. |
Wednesday, March 4, 2020 12:27PM - 1:03PM |
M58.00004: Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics talk: Quantum Chemistry in the Continuum Invited Speaker: Anna Krylov Owing to the progress in many-body theories and computer hardware, quantum chemistry tools are now routinely used in chemistry and physics, providing both high-quality quantitative data (often rivaling experimental measurements) and invaluable qualitative insights (crucial for interpretation of experimental observations). Despite its success in treating a broad range of electronic structures, ranging from ground-state closed-shell molecules to excited states and strongly correlated systems, quantum chemistry is still lagging behind when electronically metastable states (i.e, resonances embedded in the ionization continuum) are concerned. This lecture will provide an overview of the progress in extending quantum chemistry into the continuum. The main emphasis will be on exploring the ideas of non-Hermitian quantum mechanics within the framework of coupled-cluster and equation-of-motion coupled-cluster theory. |
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