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Serwatka T, Roy PN. Ground states of planar dipolar rotor chains with recurrent neural networks. J Chem Phys 2024; 160:224103. [PMID: 38856054 DOI: 10.1063/5.0205466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/27/2024] [Indexed: 06/11/2024] Open
Abstract
In this contribution, we employ a recurrent neural network (RNN) architecture in a variational optimization to obtain the ground state of linear chains of planar, dipolar rotors. We test different local basis sets and discuss their impact on the sign structure of the many-body ground state wavefunction. It is demonstrated that the RNN ansatz we employ is able to treat systems with and without a sign problem in the ground state. For larger chains with up to 50 rotors, accurate properties, such as correlation functions and Binder parameters, are calculated. By employing quantum annealing, we show that precise entanglement properties can be obtained. All these properties allow one to identify a quantum phase transition between a paraelectric and a ferroelectric quantum phase.
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Affiliation(s)
- Tobias Serwatka
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Pierre-Nicholas Roy
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Serwatka T, Roy PN. Quantum criticality in chains of planar rotors with dipolar interactions. J Chem Phys 2024; 160:104302. [PMID: 38465677 DOI: 10.1063/5.0195453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/22/2024] [Indexed: 03/12/2024] Open
Abstract
In this work, we perform a density matrix renormalization group study of chains of planar rotors interacting via dipolar interactions. By exploring the ground state from weakly to strongly interacting rotors, we find the occurrence of a quantum phase transition between a disordered and a dipole-ordered quantum state. We show that the nature of the ordered state changes from ferroelectric to antiferroelectric when the relative orientation of the rotor planes varies and that this change requires no modification of the overall symmetry. The observed quantum phase transitions are characterized by critical exponents and central charges, which reveal different universality classes ranging from that of the (1 + 1)D Ising model to the 2D classical XY model.
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Affiliation(s)
- Tobias Serwatka
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Pierre-Nicholas Roy
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Li Y, Brevik I, Malyi OI, Boström M. Different pathways to anomalous stabilization of ice layers on methane hydrates. Phys Rev E 2023; 108:034801. [PMID: 37849091 DOI: 10.1103/physreve.108.034801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 08/03/2023] [Indexed: 10/19/2023]
Abstract
We explore the Casimir-Lifshitz free-energy theory for surface freezing of methane gas hydrates near the freezing point of water. The theory enables us to explore different pathways, resulting in anomalous (stabilizing) ice layers on methane hydrate surfaces via energy minimization. Notably, we will contrast the gas hydrate material properties, under which thin ice films can form in water vapor, with those previously predicted to be required in the presence of liquid water. It is predicted that methane hydrates in water vapor near the freezing point of water nucleate ice films, instead of water films.
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Affiliation(s)
- Y Li
- School of Physics and Materials Science, Nanchang University, Nanchang 330031, China
- Institute of Space Science and Technology, Nanchang University, Nanchang 330031, China
| | - I Brevik
- Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - O I Malyi
- Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Strasse 133, 01-919, Warsaw, Poland
| | - M Boström
- Centre of Excellence ENSEMBLE3 Sp. z o. o., Wolczynska Strasse 133, 01-919, Warsaw, Poland
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Serwatka T, Roy PN. Quantum Criticality and Universal Behavior in Molecular Dipolar Lattices of Endofullerenes. J Phys Chem Lett 2023:5586-5591. [PMID: 37307244 DOI: 10.1021/acs.jpclett.3c01042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Fullerene cages allow the confinement of single molecules and the construction of molecular assemblies whose properties strongly differ from those of free species. In this work, we employ the density-matrix renormalization group method to show that chains of fullerenes filled with polar molecules (LiF, HF, and H2O) can form dipole-ordered quantum phases. In symmetry broken environments, these ordered phases are ferroelectric, a property that makes them promising candidates for quantum devices. We demonstrate that for a given guest molecule, the occurrence of these quantum phases can be enforced or influenced either by changing the effective electric dipole moment or by isotopic substitution. In the ordered phase, all systems under consideration are characterized by universal behavior that depends only on the ratio of the effective electric dipole and of the rotational constant. A phase diagram is derived, and further molecules are proposed as candidates for dipole-ordered endofullerene chains.
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Affiliation(s)
- Tobias Serwatka
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Pierre-Nicholas Roy
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Serwatka T, Yim S, Ayotte P, Roy PN. On the nature of the Schottky anomaly in endohedral water. J Chem Phys 2023; 158:124310. [PMID: 37003742 DOI: 10.1063/5.0148882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
In this work, we study the heat capacity contribution of a rigid water molecule encapsulated in C60 by performing six-dimensional eigenstate calculations with the inclusion of its quantized rotational and translational degrees of freedom. Two confinement model potentials are considered: in the first, confinement is described using distributed pairwise Lennard-Jones interactions, while in the second, the water molecule is trapped within an eccentric but isotropic 3D harmonic effective confinement potential [Wespiser et al., J. Chem. Phys. 156, 074304 (2022)]. Contributions to the heat capacity from both the ortho and para nuclear spin isomers of water are considered to enable the effects of their interconversion to be assessed. By including a symmetry-breaking quadrupolar potential energy term in the Hamiltonian, we can reproduce the experimentally observed Schottky anomaly at ∼2 K [Suzuki et al., J. Phys. Chem. Lett. 10, 1306 (2019)]. Furthermore, our calculations predict a second Schottky anomaly at ∼0.1 K resulting from the H configuration, a different orientational arrangement of the fullerene cages in crystalline solid C60. Contributions from the H configuration to CV also explain the second peak observed at ∼7 K in the experimentally measured heat capacity.
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Affiliation(s)
- Tobias Serwatka
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Spencer Yim
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Patrick Ayotte
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Pierre-Nicholas Roy
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Druchok M, Krasnov V, Krokhmalskii T, Cardoso E Bufalo T, Martins de Souza S, Rojas O, Derzhko O. Toward a quasiphase transition in the single-file chain of water molecules: Simple lattice model. J Chem Phys 2023; 158:104304. [PMID: 36922143 DOI: 10.1063/5.0133720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023] Open
Abstract
Recently, Ma et al. [Phys. Rev. Lett. 118, 027402 (2017)] have suggested that water molecules encapsulated in (6,5) single-wall carbon nanotube experience a temperature-induced quasiphase transition around 150 K interpreted as changes in the water dipoles orientation. We discuss further this temperature-driven quasiphase transition performing quantum chemical calculations and molecular dynamics simulations and, most importantly, suggesting a simple lattice model to reproduce the properties of the one-dimensional confined finite arrays of water molecules. The lattice model takes into account not only the short-range and long-range interactions but also the rotations in a narrow tube, and both ingredients provide an explanation for a temperature-driven orientational ordering of the water molecules, which persists within a relatively wide temperature range.
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Affiliation(s)
- Maksym Druchok
- Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, Svientsitskii Street 1, 79011 L'viv, Ukraine
| | - Volodymyr Krasnov
- Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, Svientsitskii Street 1, 79011 L'viv, Ukraine
| | - Taras Krokhmalskii
- Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, Svientsitskii Street 1, 79011 L'viv, Ukraine
| | | | - Sergio Martins de Souza
- Departamento de Fisica, Universidade Federal de Lavras, CP 3037, 37200-000 Lavras-MG, Brazil
| | - Onofre Rojas
- Departamento de Fisica, Universidade Federal de Lavras, CP 3037, 37200-000 Lavras-MG, Brazil
| | - Oleg Derzhko
- Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, Svientsitskii Street 1, 79011 L'viv, Ukraine
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