Potential surface walking and reaction paths for C2v beryllium + molecular hydrogen .rarw. beryllium hydride (BeH2) .fwdarw. beryllium + 2 atomic hydrogen (1A1)

O'Neal, Douglas; Taylor, Hugh S.; Simons, Jack

doi:10.1021/j150652a013

Cited by 82 publications

(26 citation statements)

References 1 publication

(1 reference statement)

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“…It was proposed that this reaction most likely takes place via C 2V symmetry. Their results were analogous to previous findings for theoretical studies on 3 the systems Be( 1 S) + H 2 f HBeH( 1 Σ g + ) and on 4 B + ( 1 S) + H 2 f HBH + ( 1 Σ g + ), BH + (X 2 Σ + ) + H( 2 S). They also speculated that the rate-limiting step in these reactions is the transfer of collision energy to the internal vibrational energy of the H-H′ diatomic molecule, which then causes the diatomic bond to lengthen and eventually rupture, allowing the reaction to ensue.…”

Section: Introductionsupporting

confidence: 90%

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Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions

Bell

Simons

1999

J. Phys. Chem. A

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Ab initio quantum chemistry is used to generate a three-dimensional reactive potential-energy surface for the collision of 1 S Al + ions with 1 ∑ g + H 2 molecules. This surface, in a tessellated and locally interpolated form, is used to generate forces for classical trajectory simulations of the 3.98 eV endothermic Al + + H 2 f AlH + + H reactions with initial conditions appropriate to a thermal H 2 sample and an Al + beam of specified center of mass collision kinetic energies in the 3-20 eV range. Our findings indicate that the reaction occurs not on (or near) the collinear path, which has no barrier above the reaction endothermicity, but via a near-C 2V insertive path which spontaneously breaks C 2V symmetry via second-order Jahn-Teller distortion to permit flux to evolve to AlH + + H products. The strong propensity to "avoid" the collinear path and to follow a higherenergy route is caused, at long range, by the ion-quadrupole interaction between Al + and H 2 and, at shorter range, by favorable overlap between the H 2 σ u and Al + 3p obitals. Examination of a large number of trajectories shows clearly that reactive collisions (1) lose much of their initial kinetic energy to the repulsive ionmolecule interfragment potential as the closed-shell Al + and H 2 approach, (2) transfer significant energy to the H-H stretching coordinate, thus weakening the H-H bond, (3) convert initial H 2 rotational motion as well as Al + to H 2 collisional angular momentum into rotational angular momentum of the HAlH + complex, "locking" the H 2 moiety into the insertive near-C 2V geometry about which twisting motion occurs, and (4) allow the Al + ion to form a new bond with whichever H atom is nearest it when the system crosses into regions of the energy surface where the H-Al-H asymmetric stretch mode becomes second-order JahnTeller unstable, thus allowing fragmentation into AlH + + H. These findings, combined with considerations of kinematic factors that distinguish among H 2 , D 2 , and HD, allow us to explain certain unusual threshold and isotope effects seen in the experimental reaction cross-section data on these reactions.

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Section: Introductionsupporting

confidence: 90%

“…5 eV (i.e., the lowest energy point on the seam) can trajectories react. In other words, for collisions with energies aboVe the thermodynamic threshold of 3…”

Section: The Pes Along the Insertive Pathmentioning

confidence: 99%

Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions

Bell

Simons

1999

J. Phys. Chem. A

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“…Steps are taken directly between minima [17,19,20], thus allowing large distances on the PES to be traversed. To do this, we first find a transition state connected to the current minimum using the eigenvector-following technique [21][22][23][24][25][26]. We then calculate the corresponding rearrangement mechanism and thereby obtain the new minimum.…”

Section: A Searching the Pesmentioning

confidence: 99%

Structural transitions and global minima of sodium chloride clusters

Doye

Wales²

1999

Phys. Rev. B

101

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In recent experiments on sodium chloride clusters structural transitions between nanocrystals with different cuboidal shapes were detected. Here we determine reaction pathways between the low energy isomers of one of these clusters, (NaCl)35Cl − . The key process in these structural transitions is a highly cooperative rearrangement in which two parts of the nanocrystal slip past one another on a {110} plane in a 110 direction. In this way the nanocrystals can plastically deform, in contrast to the brittle behaviour of bulk sodium chloride crystals at the same temperatures; the nanocrystals have mechanical properties which are a unique feature of their finite size. We also report and compare the global potential energy minima for (NaCl) N Cl − using two empirical potentials, and comment on the effect of polarization. 61.46.+w,36.40.Sx,82.30.Qt

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“…Eigenvector-following provides a powerful technique for locating minima and transition states and calculating reaction pathways [24][25][26][27][28][29]. The precise algorithms employed in the present work have been described in detail elsewhere [30,31].…”

Section: Geometry Optimizations and Rearrangement Pathwaysmentioning

confidence: 99%

Rearrangements and tunneling splittings of protonated water trimer

Wales¹

1999

The Journal of Chemical Physics

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Stationary points and rearrangement mechanisms are characterized for protonated water trimer using a variety of basis sets and density functional theory to describe electron correlation. For the largest basis sets there are three distinct low-lying minima separated in energy by only a few wave numbers. Ten distinct transition states were found with barriers spanning nearly three orders of magnitude. Several of these mechanisms should produce observable tunneling splittings.

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Potential surface walking and reaction paths for C2v beryllium + molecular hydrogen .rarw. beryllium hydride (BeH2) .fwdarw. beryllium + 2 atomic hydrogen (1A1)

Cited by 82 publications

References 1 publication

Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions

Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions

Structural transitions and global minima of sodium chloride clusters

Rearrangements and tunneling splittings of protonated water trimer

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Potential surface walking and reaction paths for C2v beryllium + molecular hydrogen .rarw. beryllium hydride (BeH2) .fwdarw. beryllium + 2 atomic hydrogen (1A1)

Cited by 82 publications

References 1 publication

Unusual Thresholds and Isotope Effects in Al+ + H2/D2/HD Reactions

Unusual Thresholds and Isotope Effects in Al+ + H2/D2/HD Reactions

Structural transitions and global minima of sodium chloride clusters

Rearrangements and tunneling splittings of protonated water trimer

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Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions

Unusual Thresholds and Isotope Effects in Al⁺ + H₂/D₂/HD Reactions