Vibrational spectroscopy and energy redistribution in hydrogen bonded systems
We investigate and analyze the vibrational properties, including H/D isotope effects, in a fundamental organic hydrogenbonded system using multiple experimental (infrared multiple photon dissociation and argon-tagged action spectroscopy)and computational techniques. The differences between simulated cluster spectroscopy of the isotopically labeled systemswere analyzed from a system-bath coupling perspective. We have found that the energy repartitioning between modes leadsto a complex spectral evolution as a function of temperature.
Poster describing some of this work: Poster 1 (This poster received the best poster award in the MWTCC 2010.). Poster 2. Poster 3.
Representative publications
85 Quantum nuclear dynamics on a distributed set of ion-trap quantum computing systems
Anurag Dwivedi, A. J. Rasmusson, Philip Richerme, Srinivasan S. Iyengar, "Quantum nuclear dynamics on a distributed set of ion-trap quantum computing systems", J. Am. Chem. Soc. ASAP (2024).
82 A reformulation of all ONIOM-type molecular fragmentation approaches using graph theory-based projection operators: Applications to dynamics, molecular potential surfaces, and machine learning and quantum computing
S. S. Iyengar, Timothy C. Ricard, Xiao Zhu, “A reformulation of all ONIOM-type molecular fragmentation approaches using graph theory-based projection operators: Applications to dynamics, molecular potential surfaces, and machine learning and quantum computing” J. Phys. Chem. A, ASAP (2023). J. Phys. Chem. A 128, 466 (2024).
Summary: We present a graph-theory-based reformulation of all ONIOM-based molecular fragmentation methods. We discuss applications to (a) accurate post-Hartree–Fock AIMD that can be conducted at DFT cost for medium-sized systems, (b) hybrid DFT condensed-phase studies at the cost of pure density functionals, (c) reduced cost on-the-fly large basis gas-phase AIMD and condensed-phase studies, (d) post-Hartree–Fock-level potential surfaces at DFT cost to obtain quantum nuclear effects, and (e) novel transfer machine learning protocols derived from these measures. Additionally, in previous work, the unifying strategy discussed here has been used to construct new quantum computing algorithms. Thus, we conclude that this reformulation is robust and accurate.
77 Quantum Computation of Hydrogen Bond Dynamics and Vibrational Spectra
P. Richerme, Melissa C. Revelle, Debadrita Saha, Miguel Angel Lopez-Ruiz, Anurag Dwivedi, Sam A. Norrell, Christopher G. Yale, Daniel Lobser, Ashlyn D. Burch, Susan M. Clark, J. M. Smith, A. Sabry, and S. S. Iyengar “Quantum Computation of Hydrogen Bond Dynamics and Vibrational Spectra”. J. Phys. Chem. Lett. 14, 7256 (2023).
Summary: Calculating observable properties of chemical systems is often classically intractable and widely viewed as a promising application of quantum information processing. Here, we introduce a new framework for solving generic quantum chemical dynamics problems using quantum logic. We experimentally demonstrate a proof-of-principle instance of our method using the QSCOUT ion-trap quantum computer, where we experimentally drive the ion-trap system to emulate the quantum wavepacket dynamics corresponding to the shared-proton within an anharmonic hydrogen bonded system. Following the experimental creation and propagation of the shared-proton wavepacket on the ion-trap, we extract measurement observables such as its time-dependent spatial projection and its characteristic vibrational frequencies to spectroscopicaccuracy (3.3 cm−1 wavenumbers, corresponding to >99.9% fidelity). Our approach introduces a new paradigm for studying the chemical dynamics and vibrational spectra of molecules and opens the possibility to describe the behavior of complex molecular processes with unprecedented accuracy.
58 Proton relays in anomalous carbocations dictate spectroscopy, stability and mechanisms: Case studies on C2H5+ and C3H3+
L. M. Sager and S. S. Iyengar, "Proton relays in anomalous carbocations dictate spectroscopy, stability and mechanisms: Case studies on C2H5+ and C3H3+" Phys. Chem. Chem. Phys. 19, 27801 (2017).
55 A Grotthuss-like proton shuttle in the anomalous C2H3+ Carbocation: Energetic and vibrational properties for isotopologues
J. Li, A. B. Pacheco, K. Raghavachari and S. S. Iyengar, "A Grotthuss-like proton shuttle in the anomalous C2H3+ Carbocation: Energetic and vibrational properties for isotopologues" Phys. Chem. Chem. Phys. 18, 29395 (2016). (Click here for supporting information.)
47 Constructing periodic phase space orbits from ab initio molecular dynamics trajectories to analyze vibrational spectra: case study of the Zundel (H5O2+) cation
S. M. Dietrick and S. S. Iyengar, "Constructing periodic phase space orbits from ab initio molecular dynamics trajectories to analyze vibrational spectra: case study of the Zundel (H5O2+) cation", In Press. J. Chem. Theory and Comp. 8 , 4876 (2012).
45 'Pump-probe' atom-centered density matrix propagation studies to gauge anharmonicity and energy repartitioning in atmospheric reactive adducts: Case study of the OH + Isoprene and OH + Butadiene reaction intermediates
A. B. Pacheco, S. M. Dietrick, P. S. Stevens and S. S. Iyengar, "'Pump-probe' atom-centered density matrix propagation studies to gauge anharmonicity and energy repartitioning in atmospheric reactive adducts: Case study of the OH + Isoprene and OH + Butadiene reaction intermediates", J. Phys. Chem. A 116 , 4108 (2012).
44 The influence of water on anharmonicity, stability and vibrational energy distribution of hydrogen-bonded adducts in atmospheric reactions: Case study of Hydroxy Isoprene using ab-initio Molecular Dynamics
S. M. Dietrick, A. B. Pacheco, P. Phatak, P. S. Stevens and S. S. Iyengar, "The influence of water on anharmonicity, stability and vibrational energy distribution of hydrogen-bonded adducts in atmospheric reactions: Case study of Hydroxy Isoprene using ab-initio Molecular Dynamics", J. Phys. Chem. A 116 , 399 (2012).
38 Isotope dependent, temperature regulated, energy repartitioning in a low-barrier, short-strong hydrogen bonded cluster
X. Li, J. Oomens, J. R. Eyler, D. T. Moore, S. S. Iyengar, "Isotope dependent, temperature regulated, energy repartitioning in a low-barrier, short-strong hydrogen bonded cluster" J. Chem. Phys. 132, 244301 (2010).
36 Computing vibrational properties in hydrogen bonded systems using Quantum wavepacket ab initio molecular dynamics
S. S. Iyengar, "Computing vibrational properties in hydrogen bonded systems using Quantum wavepacket ab initio molecular dynamics" Int. J. Quant. Chem. 109 , 3798 (2009).
32 Insights from first principles molecular dynamics studies towards infra-red multiple-photon and single-photon action spectroscopy: Case study of the proton-bound di-methyl ether dimer
X. Li, D. T. Moore and S. S. Iyengar, "Insights from first principles molecular dynamics studies towards infra-red multiple-photon and single-photon action spectroscopy: Case study of the proton-bound di-methyl ether dimer". J. Chem. Phys. 128 , 184308 (2008).
31 The study of dynamically averaged vibrational spectroscopy of atmospherically relevant clusters using ab initio molecular dynamics in conjunction with quantum wavepackets
S. S. Iyengar, X. Li and I. Sumner "The study of dynamically averaged vibrational spectroscopy of atmospherically relevant clusters using ab initio molecular dynamics in conjunction with quantum wavepackets". Adv. Quant. Chem. 55 , 333 (2008).
29 Quantum Wavepacket Ab Initio Molecular Dynamics: An approach for computing dynamically averaged vibrational spectra including critical nuclear quantum effects
I. Sumner and S. S. Iyengar "Quantum Wavepacket Ab Initio Molecular Dynamics: An approach for computing dynamically averaged vibrational spectra including critical nuclear quantum effects". J. Phys. Chem. A, 111 , 10313-10324 (2007).
28 Further analysis of the dynamically averaged vibrational spectrum for the 'magic' protonated 21-water cluster
S. S. Iyengar "Further analysis of the dynamically averaged vibrational spectrum for the 'magic' protonated 21-water cluster". J. Chem. Phys. 126 , 216101 (2007).
27 Can the four-coordinated, penta-valent oxygen in hydroxide water clusters be detected through experimental vibrational spectroscopy?
X. Li, V. E. Teige and S. S. Iyengar "Can the four-coordinated, penta-valent oxygen in hydroxide water clusters be detected through experimental vibrational spectroscopy?". J. Phys. Chem. A 111 , 4815-4820 (2007).
21 The Properties of Ion-Water Clusters. I. The Protonated 21-Water Cluster
S. S. Iyengar, M. K. Petersen, C. J. Burnham, T. J. F. Day, V. E. Teige and G. A. Voth, "The Properties of Ion-Water Clusters. I. The Protonated 21-Water Cluster". J. Chem. Phys. 123 , 084309 (2005)
20 On the Amphiphilic Behavior of the Hydrated Proton: An Ab Initio Molecular Dynamics Study
S. S. Iyengar, T. J. F. Day, and G. A. Voth, "On the Amphiphilic Behavior of the Hydrated Proton: An Ab Initio Molecular Dynamics Study". Int. J. Mass Spectrometry 241, 197-204 (2005).
18 The Hydrated Proton at the Water Liquid/Vapor Interface
M. K. Petersen, S. S. Iyengar, C. J. Burnham, T. J. F. Day, and G. A. Voth, "The Hydrated Proton at the Water Liquid/Vapor Interface". J. Phys. Chem. B 108 , 14804 (2004).
4 Symmetry-Adapted Distributed Approximating Functionals: Theory and application to the ro-vibrational states of H3+
S. S. Iyengar, G. A. Parker, D. J. Kouri, D. K. Hoffman, "Symmetry-Adapted Distributed Approximating Functionals: Theory and application to the ro-vibrational states of H3+". J. Chem. Phys. 110, 10283 (1999).
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