Exploring the Photophysical Properties of Molecular Systems Using Excited State Accelerated ab Initio Molecular Dynamics

Ab initio molecular dynamics is an irreplaceable technique for the realistic simulation of complex molecular systems and processes from first principles. This paper proposes a comprehensive and self-contained review of ab initio molecular dynamics from a computational perspective and from first principles. Quantum mechanics is presented from a molecular dynamics perspective. Various approximations and formulations are proposed, including the Ehrenfest, Born–Oppenheimer, and Hartree–Fock molecular dynamics. Subsequently, the Kohn–Sham formulation of molecular dynamics is introduced as well as the afferent concept of density functional. As a result, Car–Parrinello molecular dynamics is discussed, together with its extension to isothermal and isobaric processes. Car–Parrinello molecular dynamics is then reformulated in terms of path integrals. Finally, some implementation issues are analysed, namely, the pseudopotential, the orbital functional basis, and hybrid molecular dynamics.

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Ab Initio Molecular Dynamics Simulations of an Excited State of X-(H2O)3(X = Cl, I) Complex

The Journal of Physical Chemistry A ◽

10.1021/jp0512816 ◽

2005 ◽

Vol 109 (42) ◽

pp. 9419-9423 ◽

Cited By ~ 24

Author(s):

M. Kołaski ◽

Han Myoung Lee ◽

Chaeho Pak ◽

M. Dupuis ◽

Kwang S. Kim

Keyword(s):

Molecular Dynamics ◽

Excited State ◽

Ab Initio ◽

Molecular Dynamics Simulations ◽

Ab Initio Molecular Dynamics ◽

Dynamics Simulations

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Correction to: Canonical Quantum Observables for Molecular Systems Approximated by Ab Initio Molecular Dynamics

Annales Henri Poincaré ◽

10.1007/s00023-019-00819-x ◽

2019 ◽

Vol 20 (8) ◽

pp. 2873-2875

Author(s):

Aku Kammonen ◽

Petr Plecháč ◽

Mattias Sandberg ◽

Anders Szepessy

Keyword(s):

Molecular Dynamics ◽

Ab Initio ◽

Ab Initio Molecular Dynamics ◽

Molecular Systems ◽

Quantum Observables ◽

Canonical Quantum

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Proton Transfer from a Photoacid to Water: First Principles Simulations and Fast Fluorescence Spectroscopy

10.33774/chemrxiv-2021-cdzlk ◽

2021 ◽

Author(s):

Alice R. Walker ◽

Boning Wu ◽

Jan Meisner ◽

Michael D. Fayer ◽

Todd J. Martinez

Keyword(s):

Molecular Dynamics ◽

Excited State ◽

Fluorescence Spectroscopy ◽

Proton Transfer ◽

Ab Initio ◽

Time Constant ◽

Emission Wavelength ◽

Ab Initio Molecular Dynamics ◽

Long Distance ◽

Hydrogen Bonded

Proton transfer reactions are ubiquitous in chemistry, especially in aqueous solutions. We investigate photo-induced proton transfer between the photoacid 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) and water using fast fluorescence spectroscopy and ab initio molecular dynamics simulations. Photo-excitation causes rapid proton release from the HPTS hydroxyl. Previous experiments on HPTS/water described the progress from photoexcitation to proton diffusion using kinetic equations with two time constants. The shortest time constant has been interpreted as protonated and photoexcited HPTS evolving into an “associated” state, where the proton is “shared” between the HPTS hydroxyl and an originally hydrogen bonded water. The longer time constant has been interpreted as indicating evolution to a “solvent separated” state where the shared proton undergoes long distance diffusion. In this work, we refine the previous experimental results using very pure HPTS. We then use excited state ab initio molecular dynamics to elucidate the detailed molecular mechanism of aqueous excited state proton transfer in HPTS. We find that the initial excitation results in rapid rearrangement of water, forming a strong hydrogen bonded network (a “water wire”) around HPTS. HPTS then deprotonates in ≤3 ps, resulting in a proton that migrates back and forth along the wire before localizing on a single water molecule. We find a near linear relationship between emission wavelength and proton-HPTS distance over the simulated time scale, suggesting that emission wavelength can be used as a ruler for proton distance. Our simulations reveal that the “associated” state corresponds to a water wire with a mobile proton and that the diffusion of the proton away from this water wire (to a generalized “solvent-separated” state) corresponds to the longest experimental time constant.

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