Ab initio surface hopping excited‐state molecular dynamics approach on the basis of spin–orbit coupled states: An application to the A‐band photodissociation of CH 3 I

2018 ◽  
Vol 40 (2) ◽  
pp. 456-463 ◽  
Author(s):  
Muneaki Kamiya ◽  
Tetsuya Taketsugu
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Ab Initio ◽  
Spin Orbit ◽  
Surface Hopping

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

2005 ◽  
Vol 109 (42) ◽  
pp. 9419-9423 ◽  
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

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

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.

Ab Initio QM/MM Molecular Dynamics Study on the Excited-State Hydrogen Transfer of 7-Azaindole in Water Solution

2008 ◽  
Vol 112 (40) ◽  
pp. 9675-9683 ◽  
Author(s):  
Daisuke Kina ◽  
Akira Nakayama ◽  
Takeshi Noro ◽  
Tetsuya Taketsugu ◽  
Mark S. Gordon
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Ab Initio ◽  
Hydrogen Transfer ◽  
Water Solution

Ab initio QM/MM excited-state molecular dynamics study of coumarin 151 in water solution

2009 ◽  
Vol 109 (10) ◽  
pp. 2308-2318 ◽  
Author(s):  
Daisuke Kina ◽  
Pooja Arora ◽  
Akira Nakayama ◽  
Takeshi Noro ◽  
Mark S. Gordon ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Ab Initio ◽  
Water Solution
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