Simulation of DNMR spectra using propagator formalism and Monte Carlo method

Szalay, Zsófia; Rohonczy, János

doi:10.1016/j.jmr.2008.12.002

Cited by 6 publications

(8 citation statements)

References 14 publications

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“…11,12 Our MC calculations are similar in spirit to those cited above, but they involve processes without welldefined kinematics and occurring on much shorter time scale than that directly concerned with the line shape effects.…”

Section: Introductionmentioning

confidence: 95%

“…(10), and specifically, if τ a,b |δĤ NMR | 1, then, for short times, the NMR Hamiltonian in the exponents in Eq. (12) can be replaced by ω 0 Î zk . Accordingly, for short times the projectors involved remain invariant under transformation to the interaction representation, since each of them commutes with ω 0 Î zk + 01Q0 .…”

Section: Stochastic Origin Of the Dqr Effects-a Heuristic Modelmentioning

confidence: 99%

“…11,12 In this aspect, the differences in the nature of the instantaneous spin Hamiltonians are immaterial. What does matter from a practical point of view is the difference in time scales of random switches between the Hamiltonians.…”

Section: Monte Carlo Simulations Of Dqr Effects In Nmr Spectramentioning

confidence: 99%

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A heuristic model of damped quantum rotation effects in nuclear magnetic resonance spectra

Szymański

2011

The Journal of Chemical Physics

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The damped quantum rotation (DQR) theory describes temperature effects in NMR spectra of hindered molecular rotators composed of identical atoms arranged in regular N-gons. In the standard approach, the relevant coherent dynamics are described quantum mechanically and the stochastic, thermally activated motions classically. The DQR theory is consistent. In place of random jumps over one, two, etc., maxima of the hindering potential, here one has damping processes of certain long-lived coherences between spin-space correlated eigenstates of the rotator. The damping-rate constants outnumber the classical jump-rate constants. The jump picture is recovered when the former cluster appropriately around only as many values as the number of the latter. The DQR theory was confirmed experimentally for hindered methyl groups in solids and even in liquids above 170 K. In this paper it is shown that for three-, four-, and sixfold rotators, the Liouville space equations of NMR line shapes, derived previously with the use of the quantum mechanical reduced density matrix approach, can be be given a heuristic justification. It is based on an equation of motion for the effective spin density matrix, where the relevant spin hamiltonian contains randomly fluctuating terms. The occurrence of the latter can be rationalized in terms of fluctuations of the tunneling splittings between the torsional sublevels of the rotator, including momentary liftings of the Kramers degeneracies. The question whether such degeneracy liftings are physical or virtual is discussed. The random terms in the effective hamiltonian can be Monte Carlo modeled as piecewise constant in time, which affords the stochastic equation of motion to be solved numerically in the Hilbert spin space. For sixfold rotators, this way of calculating the spectra can be useful in the instances where the Liouville space formalism of the original DQR theory is numerically unstable.

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Section: Introductionmentioning

confidence: 95%

Section: Stochastic Origin Of the Dqr Effects-a Heuristic Modelmentioning

confidence: 99%

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A heuristic model of damped quantum rotation effects in nuclear magnetic resonance spectra

Szymański

2011

The Journal of Chemical Physics

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“…The Monte Carlo calculation of DNMR spectra of coupled spin systems is based on the simulation of the behavior of spin sets. A spin set is an ordered set of S 1 , S 2 , … S n nuclei that are uncoupled to any other nuclei apart from the elements of the spin set 20, 21. These spin sets appear in several chemical environments due to the dynamic processes (e.g., conformational motions, equilibrium reactions).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…An alternative theory of dynamic NMR describes the behavior of individual spins 17, 18. Recently, we have improved this model to describe the NMR lineshapes of coupled spin systems as well 19–21. This extended theory is based on the kinetic Monte Carlo simulation of exchange processes and the propagation of the individual density matrices of spin sets.…”

Section: Introductionmentioning

confidence: 99%

Fast calculation of DNMR spectra on CUDA‐enabled graphics card

Szalay¹,

Rohonczy²

2010

J Comput Chem

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During the past few years, general-purpose graphics processing units (GPGPUs) have become rather popular in the high performance computing community. In this study, we present an implementation of the simulation of dynamic nuclear magnetic resonance (DNMR) spectra. The algorithm is based on the kinetic Monte Carlo method and therefore can benefit from the multithreaded architecture of the GPGPU. By careful optimization of the algorithm a 30-100-fold speed increase could be achieved.

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NMR Spectroscopy and Molecular Dynamics - An Outlook

Szymański

Bernatowicz

2018

Classical and Quantum Molecular Dynamics in NMR Spectra

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Simulation of DNMR spectra using propagator formalism and Monte Carlo method

Cited by 6 publications

References 14 publications

A heuristic model of damped quantum rotation effects in nuclear magnetic resonance spectra

A heuristic model of damped quantum rotation effects in nuclear magnetic resonance spectra

Fast calculation of DNMR spectra on CUDA‐enabled graphics card

NMR Spectroscopy and Molecular Dynamics - An Outlook

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