Non‐Adiabatic Effects in Chemical Reactions: Extended Born‐Oppenheimer Equations and its Applications

Adhikari, Satrajit; Billing, Gert Due

doi:10.1002/0471433462.ch3

Cited by 35 publications

(10 citation statements)

References 49 publications

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“…͑1͒ In all previous studies [1][2][3][4][5][6][7][8]14,15,28,34 the seams are located outside the planes ͑e.g., the g-h plane, which is defined as the perpendicular plane to the seam 7͑a͒ ͒ that contain the moving test particle ͑which in the present case is the HC-NHH plane͒. In other words the methylamine creates a phenomenon where the two interacting states i.e., 1AЈ and 1AЉ, are coupled by a continuous line of cis formed by one single moving atom where all other ͑six͒ atoms of the molecule are fixed in configuration space.…”

Section: Discussionmentioning

confidence: 99%

“…In the present study five atoms, namely, the carbon, the nitrogen, two amine hydrogens, and a methyl hydrogen are assumed to form a fixed plane-the HC-NH 2 plane-and their relative motion is constrained to this plane. ͑a͒ The coordinates 1 and R 1 show the position of the test hydrogen ͑with respect to the nitrogen͒ that were varied during the ci search ͑the coordinates 2 and R 2 are held fixed during this process͒. ͑b͒ The polar coordinates q and show the position of test hydrogen with respect to an assumed point close to a ci point.…”

Section: ‫ץ‬ ‫ץ‬mentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In the present article we consider a much larger system, the methylamine molecule, CH 3 NH 2 , consisting of seven atoms. The structure of the molecule is given in Fig.…”

Section: Introductionmentioning

confidence: 99%

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An intraline of conical intersections for methylamine

Levi

Halász

Vibók

et al. 2008

The Journal of Chemical Physics

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In this article are considered the conical intersections ͑ci's͒ related to the N-H bond in the methylamine, CH 3 NH 2 , molecule. The novel feature that was revealed is that the two lowest states 1AЈ and 1AЉ are coupled by a line of cis located in HC-NHH plane-a line that is formed by moving a single hydrogen on that plane while fixing the ͑six͒ other atoms. The validity of this line was proven first by studying the singularities of the ͑angular͒ nonadiabatic coupling terms and then by revealing the degeneracy points formed by the two interacting adiabatic potential energy surfaces ͑PESs͒. A theoretical analysis indicated that the line has to be a finite closed line. We also calculated the Berry phase for a contour that surrounds this line and found it to be 3.127 rad, namely, a value reasonably close to . The existence of such lines of cis-instead of isolated cis ͑as exhibited by other n-atomic ͑n Ͼ 3͒ molecules such as HNCO or C 2 H 2 ͒-may enhance significantly the transition rate from an upper adiabatic state to a lower one. There are also numerical advantages in such situations, that is, if such a line is properly placed in that plane ͑like in the present case͒ the wave-packet treatment of the nuclei can be carried out employing a single diabatic PES instead of having to consider two coupled PESs.

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Section: Discussionmentioning

confidence: 99%

Section: ‫ץ‬ ‫ץ‬mentioning

confidence: 99%

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An intraline of conical intersections for methylamine

Levi

Halász

Vibók

et al. 2008

The Journal of Chemical Physics

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“…[27][28][29][30][31][32][33][34][35][36][37][38] In the present study of the 4 ϫ 4 state, we have adopted the procedure suggested by Werner and co-workers 22 that is based on an ab initio determination of quasidiabatic electronic wave function, and is somewhat similar to the method proposed by Pacher et al 30 In our earlier study, we utilized this procedure and obtained 2 ϫ 2 quasidiabatic PESs involving the GS and the first ES of the H + +H 2 system 39 and the quantum dynamics 40,41 carried out using these PESs under the VCC-RIOSA framework yielded the collision attributes in quantitative agreement with those obtained from experiments for E cm = 4.67-20 eV, settling some long-standing discrepancies between theory and experiment. Several quasidiabatization procedures have been proposed in the literature, and their exactness and associated advantages for numerical computations have been discussed and documented in detail.…”

Section: A Present Focusmentioning

confidence: 99%

Ab initio adiabatic and quasidiabatic potential energy surfaces of lowest four electronic states of the H++O2 system

Xavier

Kumar

2010

The Journal of Chemical Physics

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Ab initio global adiabatic and quasidiabatic potential energy surfaces of lowest four electronic (1-4 (3)A(")) states of the H(+)+O(2) system have been computed in the Jacobi coordinates (R,r,γ) using Dunning's cc-pVTZ basis set at the internally contracted multireference (single and double) configuration interaction level of accuracy, which are relevant to the dynamics studies of inelastic vibrational and charge transfer processes observed in the scattering experiments. The computed equilibrium geometry parameters of the bound [HO(2)](+) ion in the ground electronic state and other parameters for the transition state for the isomerization process, HOO(+)⇌OOH(+) are in good quantitative agreement with those available from the high level ab initio calculations, thus lending credence to the accuracy of the potential energy surfaces. The nonadiabatic couplings between the electronic states have been analyzed in both the adiabatic and quasidiabatic frameworks by computing the nonadiabatic coupling matrix elements and the coupling potentials, respectively. It is inferred that the dynamics of energy transfer processes in the scattering experiments carried out in the range of 9.5-23 eV would involve all the four electronic states.

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“…The molecular quantum dynamics become interesting in the presence of conical intersection (CI), − which is essentially responsible for the ultrafast decay processes. Such nonadiabatic or non Born–Oppenheimer (BO) phenomena − are very frequent in polyatomics and need special attention for accurate quantum treatment. The large molecular systems possessing many degrees of freedom (DOFs) can be handled in a mixed quantum-classical way because all of them are not significant in dynamics.…”

Section: Introductionmentioning

confidence: 99%

Multisurface Multimode Molecular Dynamical Simulation of Naphthalene and Anthracene Radical Cations by Using Nearly Linear Scalable Time-Dependent Discrete Variable Representation Method

et al. 2014

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The major portion of the algorithm of the time-dependent discrete variable representation (TDDVR) method is recently parallelized using the shared-memory parallelization scheme with the aim of performing dynamics on relatively large molecular systems. Because of the astronomical importance of naphthalene and anthracene, we have investigated their radical cations as models for theoretical simulation of complex photoelectron spectra and nonradiative decay process using the newly implemented parallel TDDVR code. The strong vibronic coupling among the six lowest doublet electronic states makes these polynuclear hydrocarbons dynamically important. The aim of the present investigation is to show the efficiency of our current TDDVR algorithm to perform dynamics on large dimensional quantum systems in vibronically coupled electronic manifold. Both the sequential and the parallelized TDDVR algorithms are almost linear scalable for an increase in number of processors. Because a significant speed-up is achieved by cycling in the correct way over arrays, all of the simulations are performed within a reasonable wall clock time. Our theoretical spectra well reproduce the features of the corresponding experimental analog. The dynamical outcomes, for example, population, photoelectron spectra, and diffused interstellar bands, etc., of our quantum-classical approach show good agreement with the findings of the well-established quantum dynamical method, that is, multi configuration time-dependent Hartree (MCTDH) approach.

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Non‐Adiabatic Effects in Chemical Reactions: Extended Born‐Oppenheimer Equations and its Applications

Cited by 35 publications

References 49 publications

An intraline of conical intersections for methylamine

An intraline of conical intersections for methylamine

Ab initio adiabatic and quasidiabatic potential energy surfaces of lowest four electronic states of the H++O2 system

Multisurface Multimode Molecular Dynamical Simulation of Naphthalene and Anthracene Radical Cations by Using Nearly Linear Scalable Time-Dependent Discrete Variable Representation Method

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