1
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Mazzola G. Quantum computing for chemistry and physics applications from a Monte Carlo perspective. J Chem Phys 2024; 160:010901. [PMID: 38165101 DOI: 10.1063/5.0173591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/18/2023] [Indexed: 01/03/2024] Open
Abstract
This Perspective focuses on the several overlaps between quantum algorithms and Monte Carlo methods in the domains of physics and chemistry. We will analyze the challenges and possibilities of integrating established quantum Monte Carlo solutions into quantum algorithms. These include refined energy estimators, parameter optimization, real and imaginary-time dynamics, and variational circuits. Conversely, we will review new ideas for utilizing quantum hardware to accelerate the sampling in statistical classical models, with applications in physics, chemistry, optimization, and machine learning. This review aims to be accessible to both communities and intends to foster further algorithmic developments at the intersection of quantum computing and Monte Carlo methods. Most of the works discussed in this Perspective have emerged within the last two years, indicating a rapidly growing interest in this promising area of research.
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Affiliation(s)
- Guglielmo Mazzola
- Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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2
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Van Benschoten W, Petras HR, Shepherd JJ. Electronic Free Energy Surface of the Nitrogen Dimer Using First-Principles Finite Temperature Electronic Structure Methods. J Phys Chem A 2023; 127:6842-6856. [PMID: 37535315 PMCID: PMC10440793 DOI: 10.1021/acs.jpca.3c01741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/20/2023] [Indexed: 08/04/2023]
Abstract
We use full configuration interaction and density matrix quantum Monte Carlo methods to calculate the electronic free energy surface of the nitrogen dimer within the free-energy Born-Oppenheimer approximation. As the temperature is raised from T = 0, we find a temperature regime in which the internal energy causes bond strengthening. At these temperatures, adding in the entropy contributions is required to cause the bond to gradually weaken with increasing temperature. We predict a thermally driven dissociation for the nitrogen dimer between 22,000 to 63,200 K depending on symmetries and basis set. Inclusion of more spatial and spin symmetries reduces the temperature required. The origin of these observations is explored using the structure of the density matrix at various temperatures and bond lengths.
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Affiliation(s)
| | - Hayley R. Petras
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - James J. Shepherd
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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3
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Bui AT, Thiemann FL, Michaelides A, Cox SJ. Classical Quantum Friction at Water-Carbon Interfaces. NANO LETTERS 2023; 23:580-587. [PMID: 36626824 PMCID: PMC9881168 DOI: 10.1021/acs.nanolett.2c04187] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/04/2023] [Indexed: 05/20/2023]
Abstract
Friction at water-carbon interfaces remains a major puzzle with theories and simulations unable to explain experimental trends in nanoscale waterflow. A recent theoretical framework─quantum friction (QF)─proposes to resolve these experimental observations by considering nonadiabatic coupling between dielectric fluctuations in water and graphitic surfaces. Here, using a classical model that enables fine-tuning of the solid's dielectric spectrum, we provide evidence from simulations in general support of QF. In particular, as features in the solid's dielectric spectrum begin to overlap with water's librational and Debye modes, we find an increase in friction in line with that proposed by QF. At the microscopic level, we find that this contribution to friction manifests more distinctly in the dynamics of the solid's charge density than that of water. Our findings suggest that experimental signatures of QF may be more pronounced in the solid's response rather than liquid water's.
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Affiliation(s)
- Anna T. Bui
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Fabian L. Thiemann
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
- Thomas
Young Centre, London Centre for Nanotechnology, and Department of
Physics and Astronomy, University College
London, Gower Street, LondonWC1E 6BT, United Kingdom
- Department
of Chemical Engineering, Sargent Centre for Process Systems Engineering, Imperial College London, South Kensington Campus, LondonSW7 2AZ, United Kingdom
| | - Angelos Michaelides
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
| | - Stephen J. Cox
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Lensfield Road, CambridgeCB2 1EW, United Kingdom
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4
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Nakano K, Attaccalite C, Barborini M, Capriotti L, Casula M, Coccia E, Dagrada M, Genovese C, Luo Y, Mazzola G, Zen A, Sorella S. TurboRVB: A many-body toolkit for ab initio electronic simulations by quantum Monte Carlo. J Chem Phys 2020; 152:204121. [DOI: 10.1063/5.0005037] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Kousuke Nakano
- International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
- Japan Advanced Institute of Science and Technology (JAIST), Asahidai 1-1, Nomi, Ishikawa 923-1292, Japan
| | - Claudio Attaccalite
- Aix-Marseille Université, CNRS, CINaM UMR 7325, Campus de Luminy, 13288 Marseille, France
| | | | - Luca Capriotti
- New York University, Tandon School of Engineering, 6 MetroTech Center, Brooklyn, New York 11201, USA
- Department of Mathematics, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Michele Casula
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, CNRS UMR 7590, IRD UMR 206, MNHN, 4 Place Jussieu, 75252 Paris, France
| | - Emanuele Coccia
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - Mario Dagrada
- Forescout Technologies, John F. Kennedylaan 2, 5612AB Eindhoven, The Netherlands
| | - Claudio Genovese
- International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
| | - Ye Luo
- Computational Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, USA
- Argonne Leadership Computing Facility, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, USA
| | | | - Andrea Zen
- Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Thomas Young Centre and London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH, United Kingdom
| | - Sandro Sorella
- International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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5
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Mazzola G, Sorella S. Accelerating ab initio Molecular Dynamics and Probing the Weak Dispersive Forces in Dense Liquid Hydrogen. PHYSICAL REVIEW LETTERS 2017; 118:015703. [PMID: 28106448 DOI: 10.1103/physrevlett.118.015703] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Indexed: 06/06/2023]
Abstract
We propose an ab initio molecular dynamics method, capable of dramatically reducing the autocorrelation time required for the simulation of classical and quantum particles at finite temperatures. The method is based on an efficient implementation of a first order Langevin dynamics modified by means of a suitable, position dependent acceleration matrix S. Here, we apply this technique to both Lennard-Jones models, to demonstrate the accuracy and speeding-up of the sampling, and within a quantum Monte Carlo based wave function approach, for determining the phase diagram of high-pressure hydrogen with simulations much longer than the autocorrelation time. With the proposed method, we are able to equilibrate in a few hundred steps even close to the liquid-liquid phase transition (LLT). Within our approach, we find that the LLT transition is consistent with recent density functionals predicting a much larger transition pressure when the long range dispersive forces are taken into account.
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Affiliation(s)
| | - Sandro Sorella
- International School for Advanced Studies (SISSA) Via Beirut 2, 4 34014 Trieste, Italy and INFM Democritos National Simulation Center, Via Beirut 2-4, I-34014 Trieste, Italy
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6
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Barborini M, Sorella S, Rontani M, Corni S. Correlation Effects in Scanning Tunneling Microscopy Images of Molecules Revealed by Quantum Monte Carlo. J Chem Theory Comput 2016; 12:5339-5349. [PMID: 27709944 DOI: 10.1021/acs.jctc.6b00710] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Scanning tunneling microscopy (STM) and spectroscopy probe the local density of states of single molecules electrically insulated from the substrate. The experimental images, although usually interpreted in terms of single-particle molecular orbitals, are associated with quasiparticle wave functions dressed by the whole electron-electron interaction. Here we propose an ab initio approach based on quantum Monte Carlo to calculate the quasiparticle wave functions of molecules. Through the comparison between Monte Carlo wave functions and their uncorrelated Hartree-Fock counterparts we visualize the electronic correlation embedded in the simulated STM images, highlighting the many-body features that might be observed.
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Affiliation(s)
| | - Sandro Sorella
- Scuola Internazionale Superiore di Studi Avanzati (SISSA) and CNR-IOM Democritos National Simulation Center, via Bonomea 265, 34136 Trieste, Italy
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7
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Zen A, Coccia E, Gozem S, Olivucci M, Guidoni L. Quantum Monte Carlo Treatment of the Charge Transfer and Diradical Electronic Character in a Retinal Chromophore Minimal Model. J Chem Theory Comput 2016; 11:992-1005. [PMID: 25821414 PMCID: PMC4357234 DOI: 10.1021/ct501122z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Indexed: 01/22/2023]
Abstract
![]()
The
penta-2,4-dieniminium cation (PSB3) displays similar ground
state and first excited state potential energy features as those of
the retinal protonated Schiff base (RPSB) chromophore in rhodopsin.
Recently, PSB3 has been used to benchmark several electronic structure
methods, including highly correlated multireference wave function
approaches, highlighting the necessity to accurately describe the
electronic correlation in order to obtain reliable properties even
along the ground state (thermal) isomerization paths. In this work,
we apply two quantum Monte Carlo approaches, the variational Monte
Carlo and the lattice regularized diffusion Monte Carlo, to study
the energetics and electronic properties of PSB3 along representative
minimum energy paths and scans related to its thermal cis–trans isomerization. Quantum Monte Carlo
is used in combination with the Jastrow antisymmetrized geminal power
ansatz, which guarantees an accurate and balanced description of the
static electronic correlation thanks to the multiconfigurational nature
of the antisymmetrized geminal power term, and of the dynamical correlation,
due to the presence of the Jastrow factor explicitly depending on
electron–electron distances. Along the two ground state isomerization
minimum energy paths of PSB3, CASSCF calculations yield wave functions
having either charge transfer or diradical character in proximity
of the two transition state configurations. Here, we observe that
at the quantum Monte Carlo level of theory, only the transition state
with charge transfer character can be located. The conical intersection,
which becomes highly sloped, is observed only if the path connecting
the two original CASSCF transition states is extended beyond the diradical
one, namely by increasing the bond-length-alternation (BLA). These
findings are in good agreement with the results obtained by MRCISD+Q
calculations, and they demonstrate the importance of having an accurate
description of the static and dynamical correlation when studying
isomerization and transition states of conjugated systems.
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8
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Klinduhov N, Boukheddaden K. Vibronic Theory of Ultrafast Intersystem Crossing Dynamics in a Single Spin-Crossover Molecule at Finite Temperature beyond the Born--Oppenheimer Approximation. J Phys Chem Lett 2016; 7:722-727. [PMID: 26835869 DOI: 10.1021/acs.jpclett.6b00014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Quantum density matrix theory is carried out to study the ultrafast dynamics of the photoinduced state in a spin-crossover (SC) molecule interacting with a heat bath. The investigations are realized at finite temperature and beyond the usual Born-Oppenheimer (BO) approach. We found that the SC molecule experiences in the photoexcited state (PES) a huge internal pressure, estimated at several gigapascals, partly released in an "explosive" way within ∼100 fs, causing large bond length oscillations, which dampen in the picosecond time scale because of internal conversion processes. During this regime, the BO approximation is not valid. Depending on the tunneling strength, the ultrafast relaxation may proceed through the thermodynamic metastable high-spin state or prevent it. Interestingly, we demonstrate that final relaxation toward the low-spin state always follows a local equilibrium pathway, where the BO approach is valid. Our formulation reconciles the nonequilibrium and the equilibrium properties of this fascinating phenomenon and opens the way to quantum studies on cluster molecules.
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Affiliation(s)
- Nikolay Klinduhov
- Groupe d'Etude de la Matière Condensée, Université de Versailles, CNRS UMR 8635 , 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France
- Institute of Technical Acoustics, National Academy of Sciences of Belarus , 13 Lyudnikova st, 210023 Vitebsk, Belarus
| | - Kamel Boukheddaden
- Groupe d'Etude de la Matière Condensée, Université de Versailles, CNRS UMR 8635 , 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France
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9
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Yang Y, Kylänpää I, Tubman NM, Krogel JT, Hammes-Schiffer S, Ceperley DM. How large are nonadiabatic effects in atomic and diatomic systems? J Chem Phys 2015; 143:124308. [DOI: 10.1063/1.4931667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yubo Yang
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
| | - Ilkka Kylänpää
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
- Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
| | - Norm M. Tubman
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
| | - Jaron T. Krogel
- Oak Ridge National Laboratory, Materials Sciences & Technology Division, Oak Ridge, Tennessee 37831, USA
| | | | - David M. Ceperley
- Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
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10
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Barborini M, Guidoni L. Ground State Geometries of Polyacetylene Chains from Many-Particle Quantum Mechanics. J Chem Theory Comput 2015; 11:4109-18. [PMID: 26405437 PMCID: PMC4570661 DOI: 10.1021/acs.jctc.5b00427] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Indexed: 11/28/2022]
Abstract
Due to the crucial role played by electron correlation, the accurate determination of ground state geometries of π-conjugated molecules is still a challenge for many quantum chemistry methods. Because of the high parallelism of the algorithms and their explicit treatment of electron correlation effects, Quantum Monte Carlo calculations can offer an accurate and reliable description of the electronic states and of the geometries of such systems, competing with traditional quantum chemistry approaches. Here, we report the structural properties of polyacetylene chains H-(C₂H₂)(N)-H up to N = 12 acetylene units, by means of Variational Monte Carlo (VMC) calculations based on the multi-determinant Jastrow Antisymmetrized Geminal Power (JAGP) wave function. This compact ansatz can provide for such systems an accurate description of the dynamical electronic correlation as recently detailed for the 1,3-butadiene molecule [J. Chem. Theory Comput. 2015 11 (2), 508-517]. The calculated Bond Length Alternation (BLA), namely the difference between the single and double carbon bonds, extrapolates, for N → ∞, to a value of 0.0910(7) Å, compatible with the experimental data. An accurate analysis was able to distinguish between the influence of the multi-determinantal AGP expansion and of the Jastrow factor on the geometrical properties of the fragments. Our size-extensive and self-interaction-free results provide new and accurate ab initio references for the structures of the ground state of polyenes.
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Affiliation(s)
- Matteo Barborini
- Dipartimento
di Ingegneria e Scienze dell’Informazione e Matematica, Università degli studi dell’Aquila, Via Vetoio (Coppito), 67100 L’Aquila, Italy
- Dipartimento
di Scienze Fisiche e Chimiche, Università
degli studi dell’Aquila, Via Vetoio (Coppito), 67100 L’Aquila, Italy
| | - Leonardo Guidoni
- Dipartimento
di Scienze Fisiche e Chimiche, Università
degli studi dell’Aquila, Via Vetoio (Coppito), 67100 L’Aquila, Italy
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11
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Zen A, Luo Y, Mazzola G, Guidoni L, Sorella S. Ab initio molecular dynamics simulation of liquid water by quantum Monte Carlo. J Chem Phys 2015; 142:144111. [PMID: 25877566 DOI: 10.1063/1.4917171] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Although liquid water is ubiquitous in chemical reactions at roots of life and climate on the earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article, we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in good agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous density functional theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab initio simulations of complex chemical systems.
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Affiliation(s)
- Andrea Zen
- Dipartimento di Fisica, “La Sapienza” - Università di Roma, piazzale Aldo Moro 5, 00185 Rome, Italy
- London Centre for Nanotechnology, University College London, London WC1E 6BT, United Kingdom
| | - Ye Luo
- SISSA–International School for Advanced Studies, Via Bonomea 26, 34136 Trieste, Italy
- Democritos Simulation Center CNR–IOM Istituto Officina dei Materiali, 34151 Trieste, Italy
| | - Guglielmo Mazzola
- SISSA–International School for Advanced Studies, Via Bonomea 26, 34136 Trieste, Italy
- Democritos Simulation Center CNR–IOM Istituto Officina dei Materiali, 34151 Trieste, Italy
| | - Leonardo Guidoni
- Dipartimento di Fisica, “La Sapienza” - Università di Roma, piazzale Aldo Moro 5, 00185 Rome, Italy
- Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell’ Aquila, via Vetoio, 67100 L’ Aquila, Italy
| | - Sandro Sorella
- SISSA–International School for Advanced Studies, Via Bonomea 26, 34136 Trieste, Italy
- Democritos Simulation Center CNR–IOM Istituto Officina dei Materiali, 34151 Trieste, Italy
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12
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Mazzola G, Sorella S. Distinct metallization and atomization transitions in dense liquid hydrogen. PHYSICAL REVIEW LETTERS 2015; 114:105701. [PMID: 25815949 DOI: 10.1103/physrevlett.114.105701] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Indexed: 06/04/2023]
Abstract
We perform molecular dynamics simulations driven by accurate quantum Monte Carlo forces on dense liquid hydrogen. There is a recent report of a complete atomization transition between a mixed molecular-atomic liquid and a completely dissociated fluid in an almost unaccessible pressure range [Nat. Commun. 5, 3487 (2014)]. Here, instead, we identify a different transition between the fully molecular liquid and the mixed-atomic fluid at ∼400 GPa, i.e., in a much more interesting pressure range. We provide numerical evidence supporting the metallic behavior of this intermediate phase. Therefore, we predict that the metallization at finite temperature occurs in this partially dissociated molecular fluid, well before the complete atomization of the liquid. At high temperature this first-order transition becomes a crossover, in very good agreement with the experimental observation. Several systematic tests supporting the quality of our large scale calculations are also reported.
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Affiliation(s)
- Guglielmo Mazzola
- International School for Advanced Studies (SISSA), and CRS Democritos, CNR-INFM, -Via Bonomea 265, I-34136 Trieste, Italy
| | - Sandro Sorella
- International School for Advanced Studies (SISSA), and CRS Democritos, CNR-INFM, -Via Bonomea 265, I-34136 Trieste, Italy
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13
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Zen A, Coccia E, Luo Y, Sorella S, Guidoni L. Static and Dynamical Correlation in Diradical Molecules by Quantum Monte Carlo Using the Jastrow Antisymmetrized Geminal Power Ansatz. J Chem Theory Comput 2014; 10:1048-61. [DOI: 10.1021/ct401008s] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Andrea Zen
- Dipartimento
di Fisica, Sapienza-Università di Roma, Piazzale Aldo Moro
5, 00185 Rome, Italy
| | - Emanuele Coccia
- Dipartimento
di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio 2, 67010 L’Aquila, Italy
| | - Ye Luo
- Scuola
Internazionale Superiore di Studi Avanzati (SISSA) and Democritos
National Simulation Center, Istituto Officina dei Materiali del CNR, via Bonomea 265, 34136 Trieste, Italy
| | - Sandro Sorella
- Scuola
Internazionale Superiore di Studi Avanzati (SISSA) and Democritos
National Simulation Center, Istituto Officina dei Materiali del CNR, via Bonomea 265, 34136 Trieste, Italy
| | - Leonardo Guidoni
- Dipartimento
di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio 2, 67010 L’Aquila, Italy
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14
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Reboredo FA, Kim J. Generalizing the self-healing diffusion Monte Carlo approach to finite temperature: A path for the optimization of low-energy many-body bases. J Chem Phys 2014; 140:074103. [DOI: 10.1063/1.4861222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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15
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Coccia E, Varsano D, Guidoni L. Ab Initio Geometry and Bright Excitation of Carotenoids: Quantum Monte Carlo and Many Body Green's Function Theory Calculations on Peridinin. J Chem Theory Comput 2014; 10:501-6. [PMID: 26580027 PMCID: PMC4864508 DOI: 10.1021/ct400943a] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu(+)-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu(+)-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.
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Affiliation(s)
- Emanuele Coccia
- Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, via Vetoio, 67110 L’Aquila, Italy
| | - Daniele Varsano
- S3 Center, CNR Institute of Nanoscience, Via Campi 213/A, 41125 Modena, Italy
| | - Leonardo Guidoni
- Dipartimento di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, via Vetoio, 67110 L’Aquila, Italy
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16
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Varsano D, Barborini M, Guidoni L. Kohn-Sham orbitals and potentials from quantum Monte Carlo molecular densities. J Chem Phys 2014; 140:054102. [DOI: 10.1063/1.4863213] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Zen A, Luo Y, Sorella S, Guidoni L. Molecular Properties by Quantum Monte Carlo: An Investigation on the Role of the Wave Function Ansatz and the Basis Set in the Water Molecule. J Chem Theory Comput 2013; 9:4332-4350. [PMID: 24526929 PMCID: PMC3920371 DOI: 10.1021/ct400382m] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the wave function and its variational flexibility are crucial points for both the accurate description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different variational ansatzes, several properties of the water molecule, namely, the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on variational Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Through a systematic study, we provide a useful guide to the choice of the wave function, the pseudopotential, and the basis set for QMC calculations. We also introduce a new method for the computation of forces with finite variance on open systems and a new strategy for the definition of the atomic orbitals involved in the Jastrow-Antisymmetrised Geminal power wave function, in order to drastically reduce the number of variational parameters. This scheme significantly improves the efficiency of QMC energy minimization in case of large basis sets.
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Affiliation(s)
- Andrea Zen
- Dipartimento di Fisica, La Sapienza—Università di Roma, Piazzale Aldo Moro 2, 00185 Rome, Italy
| | - Ye Luo
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Sandro Sorella
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Leonardo Guidoni
- Dipartimento di Scienze Fisiche e Chimiche, Università degli studi de L’Aquila, Via Vetoio, 67100 Coppito, L’Aquila, Italy
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Barborini M, Guidoni L. Reaction pathways by quantum Monte Carlo: insight on the torsion barrier of 1,3-butadiene, and the conrotatory ring opening of cyclobutene. J Chem Phys 2012; 137:224309. [PMID: 23249005 PMCID: PMC3925821 DOI: 10.1063/1.4769791] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantum Monte Carlo (QMC) methods are used to investigate the intramolecular reaction pathways of 1,3-butadiene. The ground state geometries of the three conformers s-trans, s-cis, and gauche, as well as the cyclobutene structure are fully optimised at the variational Monte Carlo (VMC) level, obtaining an excellent agreement with the experimental results and other quantum chemistry high level calculations. Transition state geometries are also estimated at the VMC level for the s-trans to gauche torsion barrier of 1,3-butadiene and for the conrotatory ring opening of cyclobutene to the gauche-1,3-butadiene conformer. The energies of the conformers and the reaction barriers are calculated at both variational and diffusional Monte Carlo levels providing a precise picture of the potential energy surface of 1,3-butadiene and supporting one of the two model profiles recently obtained by Raman spectroscopy [Boopalachandran et al., J. Phys. Chem. A 115, 8920 (2011)]. Considering the good scaling of QMC techniques with the system's size, our results also demonstrate how variational Monte Carlo calculations can be applied in the future to properly investigate the reaction pathways of large and correlated molecular systems.
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Affiliation(s)
- Matteo Barborini
- Dipartimento di Matematica Pura ed Applicata, Università degli studi dell'Aquila, via Vetoio (Coppito 2), 67100 L'Aquila, Italy
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