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Professor Pierre-Nicholas Roy, University of Waterloo, "Simulating Quantum Critical Molecular Assemblies: From Path Integrals to Matrix Product States"

Event Type
Professor Nancy Makri, Physical Chemistry
Oct 25, 2023   2:00 - 3:00 pm  
Randy Prince
Originating Calendar
Chemistry - Physical Chemistry Seminars

Simulating quantum critical molecular assemblies: from path integrals to matrix product states When molecules are confined in nano-cavities such as fullerenes, their translational degrees of freedom become quantized. The molecules however retain well-defined rovibrational levels [1]. These building blocks are termed endofullerenes with H2O@C60 as a prime example [2]. The endofullerenes can themselves be embedded in larger nanostructures such as carbon nanotubes to form so-called endofullerene peapods [3,4]. In such an assembly, polar molecules will interact with each other via dipole-dipole interactions. Depending on the strength of the interactions and on the monomer’s rovibrational level spacings, these system can undergo a phase transition from an disordered to ordered phase. This phenomenon is called a Quantum Phase Transition (QPT) [5]. Such a QPT was recently predicted for the case of one water in one dimension [6]. An important computational tool for the study of quantum chains of rotors is the density matrix renormalization group (DMRG) [7-9] and we will present the features of that approach. We will present recent results obtained using DMRG and will explore the concept of a quantum phase transition in the context of chains of asymmetric tops molecules like water. We will finally present conditions under which water chains can become ferroelectric [10,11]. As current DMRG approaches are most efficient for one-dimensional chains, we will discuss alternative computational approaches based on Path Integral Monte Carlo to compute two and three dimensional assemblies.

[1] C. Beduz,  et al., “Quantum rotation of ortho and para-water encapsulated in a fullerene cage,” Proc. Natl. Acad. Sci. U.S.A. 109, 12894–12898 (2012).

[2] K. Kurotobi and Y. Murata, “A single molecule of water encapsulated in fullerene c60,” Science 333, 613– 616 (2011).

[3] T. Halverson, D. Iouchtchenko, and P.-N. Roy, J. Chem. Phys. 148, 074112 (2018).

[4] J. Biskupek, et al., “Bond dissociation and re- activity of hf and h2o in a nano test tube,” ACS Nano 14, 11178–11189 (2020).

[5] S. Sachdev and B. Keimer, “Quantum criticality,” Phys. Today 64, 29 (2011).

[6] T. Serwatka, R. G. Melko, A. Burkov, and P.-N. Roy, “Quantum phase transition in the one-dimensional water chain,” Phys. Rev. Lett. 130, 026201 (2023).

[7] S. R. White, “Density matrix formulation for quan- tum renormalization groups,” Phys. Rev. Lett 69, 2863 (1992).

[8]  M. Fishman, S. White, and E. Stoudenmire, “The itensor software library for tensor network calculations,” SciPost Physics Codebases , 004 (2022).

[9] T. Serwatka and P.-N. Roy, “Ground state of asymmetric tops with dmrg: Water in one dimension,” J. Chem. Phys. 156, 044116 (2022).

[10] T. Serwatka and P.-N. Roy, “Ferroelectric water chains in carbon nanotubes: Creation and manipulation of ordered quantum phases,” J. Chem. Phys. 157, 234301 (2022).

[11] T. Serwatka and P.-N. Roy, “Quantum Criticality and Universal Behavior in Molecular Dipolar Lattices of Endofullerenes”, J. Phys. Chem. Lett., 14, 5586 (2023).

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