Mode-Specific Tunneling Splittings for a Sequential Double-Hydrogen Transfer Case: An Accurate Quantum Mechanical Scheme.
We present the first accurate quantum dynamics calculations of mode-specific tunneling splittings in a sequential double-hydrogen transfer process. This is achieved in the vinylidene-acetylene system, the simplest molecular system of this kind, and by large-scale parallel computations with an efficient theoretical scheme developed by us. In our scheme, basis functions are customized for the hydrogen transfer process; a 4-dimensional basis contraction strategy is combined with the preconditioned inexact spectral transform method; efficient parallel implementation is achieved. Mode-specific permutation tunneling splittings of vinylidene states are reported and tremendous mode-specific promotion effects are revealed; in particular, the CH2 rock mode enhances the ground-state splitting by a factor of 10(3). We find that the ground-state vinylidene has a reversible-isomerization time of 622 ps, much longer than all previous estimates. Our calculations also shed light on the importance of the deep intermediate well and vibrational excitation in the double-hydrogen transfer processes.
†Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.|‡University of Chinese Academy of Sciences, Beijing 100049, China.
Yinghui
Y
Ren
†Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Wensheng
W
Bian
D000114:Acetylene / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D007192:Indenes / Q000737:chemistry; D008956:Models, Chemical; D011789:Quantum Theory; D014753:Vinyl Compounds / Q000737:chemistry
D007192:Indenes; D014753:Vinyl Compounds; C545570:vinylindene; D006859:Hydrogen; D000114:Acetylene
double hydrogen transfer; large amplitude motion; permutation splitting; quantum tunneling; vinylidene−acetylene isomerization