J. W. Bevan

Texas A&M University, College Station, Texas, United States

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Publications (107)246.47 Total impact

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    ABSTRACT: Canonical approaches are applied for investigation of the extraordinarily accurate electronic ground state potentials of H2(+), H2, HeH(+), and LiH using the Virial Theorem. These approaches will be dependent on previous investigations involving the canonical nature of E(R), the Born-Oppenheimer potential, and F(R), the associated force of E(R), that have been demonstrated to be individually canonical to high accuracy in the case of the systems investigated. Now, the canonical nature of the remaining functions in the Virial Theorem [the electronic kinetic energy T(R), the electrostatic potential energy V(R), and the function W(R) = RF(R)] are investigated and applied to H2, HeH(+), and LiH with H2(+) chosen as reference. The results will be discussed in the context of a different perspective of molecular bonding that goes beyond previous direct applications of the Virial Theorem.
    No preview · Article · Jan 2016 · The Journal of Physical Chemistry A
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    ABSTRACT: A proof-of-concept for the accurate generation of multidimensional intermolecular interaction potentials is demonstrated. The basis for evaluating this application is the available very accurate 3-D morphed potential of Ar·HBr. Starting from the well-defined potential of the simplest molecule, the diatomic H2+, a recently developed 1-D canonical potential is used with selected 2-D polyatomic data to generate the adiabatic intermolecular interaction potential in Ar·HBr, with HBr in the vibrational ground state. This represents the first application of canonical transformations to a higher vibrationally dimensional molecular system, in this case, Ar·HBr. Results indicate intrinsic bonding characteristics inherent to both systems.
    No preview · Article · Sep 2015 · Chemical Physics Letters
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    ABSTRACT: Rovibrational transitions associated with tunneling states in the water bending vibration of the atmospherically significant N2–H2O complex have been recorded using a cw supersonic jet quantum cascade laser spectrometer at 6.2 μm. Analysis of the observed spectra is facilitated by incorporating fits of previously recorded microwave and submillimeter data. This accounts for Coriolis coupling to obtain the levels of the ground vibrational state and confirmation of assignment of the excited water bending vibration. The results are used to explore the nature of the associated water bending vibrationally excited states of the complex compared to those in other corresponding water complexes.
    No preview · Article · Jul 2015 · Chemical Physics Letters
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    ABSTRACT: A generalized formulation of canonical transformations and spectra are used to investigate the concept of a canonical potential strictly within the Born-Oppenheimer approximation. Data for the most accurate available ground electronic state pairwise intermolecular potentials in H2, HD, D2, HeH(+), and LiH are used to rigorously evaluate such transformations. The corresponding potentials are generated explicitly using parameters calculated with algebraic functions from that of the single canonical potential of the simplest molecule, H2(+). The efficacy of this approach is further tested by direct comparison of the predicted eigenvalues of all vibrational states in the selected molecular systems considered with the corresponding most accurately known Born-Oppenheimer eigenvalues currently available. Deviations are demonstrated to be less than 2 cm(-1) for all vibrational states in H2, HD, D2, HeH(+), and LiH with an average standard deviation of 0.27 cm(-1) for the 87 states considered. The implications of these results for molecular quantum chemistry will be discussed.
    No preview · Article · Jun 2015 · The Journal of Physical Chemistry A
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    ABSTRACT: A generalized formulation of explicit force-based transformations is introduced to investigate the concept of a canonical potential in both fundamental chemical and intermolecular bonding. Different classes of representative ground electronic state pairwise interatomic interactions are referenced to a chosen canonical potential illustrating application of such transformations. Specifically, accurately determined potentials of the diatomic molecules H2, H2+, HF, LiH, argon dimer, and one-dimensional dissociative coordinates in Ar-HBr, OC-HF, and OC-Cl2 are investigated throughout their bound potentials. Advantages of the current formulation for accurately evaluating equilibrium dissociation energies and a fundamentally different unified perspective on nature of intermolecular interactions will be emphasized. In particular, this canonical approach has significance to previous assertions that there is no very fundamental distinction between van der Waals bonding and covalent bonding or for that matter hydrogen and halogen bonds.
    No preview · Article · May 2015 · Physical Chemistry Chemical Physics
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    ABSTRACT: The ν1 spectra of 16O12C-DI and 16O12C-ID, as well as ν2 of 16O12C-DI, 16O12C-ID have been recorded using a quantum cascade laser pulsed slit supersonic jet spectrometer. Intensity measurements made simultaneously in the same expansion for transitions in ν2 16O12C-HI: 16O12C-IH and ν1 16O12C-DI: 16O12C-ID isomers permit determination of the isomerization for the former pair to be +2.8(1.0) and the latter −6.0(1.0) cm−1. These results confirm prediction of ground state deuterium isotopic isomerization made using a generated morphed potential. Further analyses indicate OC.HI is a prototype for complexities associated with isomerization and isotopic effects in excited stretching vibrations.
    No preview · Article · Jan 2015 · Chemical Physics Letters
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    ABSTRACT: Different classes of ground electronic state pairwise interatomic interactions are referenced to a single canonical potential using explicit transformations. These approaches have been applied to diatomic molecules N2, CO, H2(+), H2, HF, LiH, Mg2, Ca2, O2; argon dimer, and one-dimensional cuts through multidimensional potentials of OC-HBr, OC-HF, OC-HCCH, OC-HCN, OC-HCl, OC-HI, OC-BrCl, and OC-Cl2 using accurate semi-empirically determined interatomic Rydberg-Klein-Rees (RKR) and morphed intermolecular potentials. These different bonding categories are represented in these systems which vary from van der Waals, halogen bonding, hydrogen bonding to strongly bound covalent molecules with binding energies covering three orders of magnitude from 84.5 cm(-1) to 89600.6 cm(-1) in ground state dissociation energies. Such approaches were then utilized to give a unified perspective on the nature of bonding in the whole range of diatomic and intermolecular interactions investigated.
    No preview · Article · Jul 2014 · The Journal of Physical Chemistry A
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    ABSTRACT: A five-dimensional compound-model morphed (CMM) potential has been generated for the halogen bonded intermolecular interaction 16O12C-79Br35Cl based on a fit to the currently generated infrared and previously available microwave spectroscopic data. The experimentally determined blue frequency shift of the 16O12C stretching frequency on complexation with 79Br35Cl is found to be Δν = 12.89643(28) cm-1 indicating a more strongly bound complex than in OC-35Cl2. Re center-of-mass to center-of-mass distance of 4.270(7) Å and dissociation energies De = 778(70) cm-1 and D0 = 605(70) cm-1 are predicted from the CMM potential and also compared with the corresponding values of Re = 4.742(3) Å and De = 544(5) cm-1 and D0 = 397(5) cm-1 for 16O12C-35Cl2. The molecular dynamics, binding energy and other molecular parameters of OC-BrCl are also compared with the hydrogen bonded dimers OC-HX (X = F, Cl, Br) giving further insight into the characteristics of the complex.
    No preview · Article · Nov 2013 · Chemical Physics
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    ABSTRACT: Potential morphing has been applied to the investigation of proper blue frequency shifts, Δν0 in CO, the hydrogen acceptor complexing in the hydrogen bonded series OC-HX (X=F, Cl, Br, I, CN, CCH). Linear correlations of morphed hydrogen bonded ground dissociation energies D0 with experimentally determined Δν0 free from matrix and solvent effects demonstrate consistency with original tenets of the Badger-Bauer rule [J. Chem. Phys. 5, 839-51(1937)]. A model is developed that provides a basis for explaining the observed linear correlations in the range of systems studied. Furthermore, the generated calibration curve enables prediction of dissociation energies for other related but different complexes. The latter include D0 for H2O-CO, H2S-CO and OC-HOCH3 which are predicted by interpolation and found to be 355(13), 171(11) and 377(14) cm(-1) respectively from available experimentally determined proton acceptor shifts. Results from this study will also be discussed in relation to investigations in which CO has been used as a probe of heme protein active sites.
    No preview · Article · Jul 2013 · The Journal of Physical Chemistry A
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    ABSTRACT: Rovibrational manifolds in low frequency intermolecular vibrations of prototypical hydrogen-bonded interactions OC–HX (X = F, Cl, CN) are reported using a near infrared quantum cascade cw supersonic jet spectrometer. (i) OC–HCl is studied to evaluate future capabilities of the QCL spectrometer. (ii) Analysis of OC–HF demonstrates applicability to vibrations greater than 80 cm−1 above the ground state. ν51 band origins in OC–1H35Cl and OC–1H19F are 48.9944(2) and 81.96825(12) cm−1 respectively. (iii) The corresponding intermolecular ν71 band origin of OC–HCN is 34.63742(18) cm−1 and its corresponding rovibrational spectrum made available for attempted detection in interstellar space. Analysis of ν2, ν2+ν71-ν71, ν2+ν71, and ν2+ν61 vibrations in OC–HCN also enables generation of its 5-dimensional semi-empirical intermolecular potential. Structural and other properties of OC–HCN are then compared with corresponding properties predicted using morphed potentials for the homologous series OC–HX (X = F, Cl, Br, I). These results permit investigation of blue shifts in OC vibrations for this homologous series.
    No preview · Article · Dec 2012 · Chemical Physics
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    ABSTRACT: A recently generated six-dimensional vibrationally-complete compound-model morphed (CMM-RS) potential for the pairwise interaction between OC and HF is used to predict spectroscopic and other properties of the isomer CO–HF. The equilibrium dissociation energy and internuclear diatomic center-of-mass center-of-mass distances are evaluated respectively as De = 643(10) cm−1 and Re = 3.442(2) Å with an energy difference ΔE between the OC–HF and CO–HF minima in the potential energy surface of 667(10) cm−1. The CO–HF isomer is also predicted to have a local minimum state with dissociation energy D0 = 310.5(50) cm−1 which corresponds to 432(10) cm−1 above the ground state of OC–HF. Band origins for its fundamental vibrations are predicted to be: ν1 = 3938.85(100) cm−1, ν2 = 2134.52(100) cm−1, ν3 = 80.56(100) cm−1, ν41 = 205.65(100) cm−1, and ν51 = 39.55(100) cm−1 and can be compared with currently available data from matrix isolation and other spectroscopic techniques. Such predictions will also facilitate future gas phase spectroscopic investigations of the CO–HF isomeric species and ultimately critical evaluation of the predictive capabilities of the available CMM-RS potential as well as those of previously published ab initio potentials.
    No preview · Article · Sep 2012 · Journal of Molecular Structure
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    ABSTRACT: Spectroscopic studies of the OC:HCCH complex are reported using a continuous supersonic slit jet spectrometer with broadband frequency mode-hop free tunable infrared quantum cascade lasers (QCL), centered at 4.4 and 4.6 μm. This Letter includes an extended analysis of the ν3 CO stretching vibration frequency, and investigation of the ν3 + ν91 − ν91 hot band, the ν3 + ν91 and ν3 + ν81 combination bands for OC–HCCH. The ground state low frequency bend, ν91, is determined at 20.48361(20) cm−1. The generated rovibrational data is incorporated with previously determined information and used to generate a four-dimensional compound-model morphed potential with radial correction, giving further insight into the molecular dynamics of this complex.
    No preview · Article · Jan 2012 · Chemical Physics Letters
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    ABSTRACT: Transitions associated with the vibrations ν₁, ν₁ + ν(b)¹, ν₁ + ν₅¹, and ν₁ + ν₅¹ - ν₅¹ of the complex OC···Cl₂ have been rovibrationally analyzed for several isotopologues involving isotopic substitutions in Cl₂. Spectra were recorded using a recently constructed near-infrared (4.34 to 4.56 μm), quantum-cascade laser spectrometer with cw supersonic slit jet expansion. Spectral analysis allowed precise determination of the ν₅¹ intermolecular vibration of OC-³⁵Cl₂ to be 25.977637(80) cm⁻¹. These results were incorporated with other previously determined data into a spectroscopic database for generation of a five-dimensional morphed potential energy surface. This compound-model morphed potential with radial shifting (CMM-RS) was then used to make more accurate predictions of properties of the OC-³⁵Cl₂ complex including D(e) = 544(5) cm⁻¹, D₀ = 397(5) cm⁻¹, ν₃ = 56.43(4) cm⁻¹, and ν(b)¹ = 85.43(4) cm⁻¹. The CMM-RS potential determined for OC-Cl₂ was also used to compare quantitatively many of the inherent properties of this non-covalent halogen bonded complex with those of the closely related hydrogen-bonded complex OC-HCl, which has a similar dissociation energy D₀. We found that in the ground state, the CO bending amplitude is larger in OC-Cl₂ than in OC-HCl.
    No preview · Article · Dec 2011 · The Journal of Physical Chemistry A
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    ABSTRACT: A 6-dimensional vibrationally-complete compound-model morphed potential with radial shifting (CMM-RS) has been generated for the hydrogen-bonded dimer OC–HF. Four morphing parameters only are optimized correcting for inadequacies in the underlying ab initio potential. The morphing transformation utilized a rotationally resolved spectroscopic database composed of microwave and near infrared spectroscopic information. Band origin vibrational frequencies are fitted to an average standard deviation of 0.016cm−1. The equilibrium rotational constant of OC–HF is determined to be Be=3345.68(30)MHz, equilibrium center of mass CO to center of mass HF distance, Re=3.598(1)Å, and equilibrium dissociation energy De=1310(10)cm−1. Ground state dissociation energy D0=742.5(50)cm−1, first order anharmonic constants and other properties of the complex are also evaluated. Characteristics of the CMM-RS potential can also be compared with predictions using previous ab initio potentials. Limitations of the morphing methodology and its potential applications are also discussed.
    No preview · Article · Nov 2011 · Chemical Physics
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    ABSTRACT: Application of tunable infrared lasers to the spectroscopic investigation of equilibrium, gaseous hydrogen-bonded systems is demonstrated. Broadband spectra of the nν6 + ν1 − nν6 vibrations in and have been recorded with a computer-controlled multimode color center laser using both conventional absorption and infrared-acoustic detection methods.
    Preview · Article · Feb 2011 · Canadian Journal of Chemistry
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    ABSTRACT: A broadband v3 sub-Doppler spectrum of HCN has been recorded in the range 3340–3280 cm−1 using a single frequency continuously scanable computer-controlled color center laser optothermal molecular beam spectrometer. Absolute frequencies for rovibrational transitions R(9) through P(9) have been determined to an accuracy ≤ 20 MHz or 2 parts in 107. An unconstrained five-parameter fit to this datum results in molecular constants: B″ = 1.47822146(182), D″ = 2.881(23) × 10−6, B′ = 1.46779974(154), D′ = 2.863(18) × 10−6, and v0 = 3311.47758(2) cm−1, respectively.
    No preview · Article · Feb 2011 · Canadian Journal of Chemistry
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    ABSTRACT: The HI homodimer was found to have structural and vibrational properties unlike any other previously studied (HX)2 system, with X F, Cl, and Br. The infrared spectrum of (HI)2 is also observed to be distinctly different from the other members of the series. In addition, the interaction energy of the (HI)2 dimer has been calculated using the coupled-cluster with singles, doubles, and perturbative triples [CCSD(T)] level of theory. A four-dimensional morphed intermolecular potential has been generated and then morphed using available near infrared and submillimeter spectroscopic data recorded in supersonic jet expansions. The morphed potential is found to have a single global minimum with a symmetric structure having C2h symmetry. The equilibrium dissociation energy is found to be 359 cm-1 with the geometry in Jacobi coordinates of Re 4.35 , 1 43, 2 137, and 180. The infrared spectrum is characterized by pairs of excited vibrational states resulting from the coupling of the two HI stretching modes. A qualitative model using a quadratic approximation has been fitted to obtain an estimate of this coupling. Furthermore, a morphed intermolecular potential for the vibrationally excited system was also obtained that gives a quantitative estimate of the shift in the potential due to the excitation. The submillimeter analysis is consistent with a ground state having its highest probability as a paired hydrogen bond configuration with R0 4.56372(1) and an average angle =cos-1(cos 21/2) 46.40(1) (between the diatom center of masscenter of mass axis and direction of each component hydrogen iodide molecule). On monodeuteration, however, the ground state is predicted to undergo an anomalous structural isotope change to an L-shaped HI-DI structure with highest probability at R 0 4.51, 183, 2177, and 180. These results provide a test for large scale ab initio calculations and have implications for the interpretation of photoinduced chemistry and other properties of the dimer.
    Full-text · Article · Feb 2011 · The Journal of Chemical Physics
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    ABSTRACT: Design and testing of a THz sensor ultimately to be capable of operating from 0.068 to 8.1 THz are presented. Results for modular approaches in the mm and submm spectral regions are reported utilizing cavity-enhanced techniques. Investigations indicate ppq levels of detection for molecular species with 1.0 Debyes dipole moment.
    No preview · Article · Jan 2011
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    ABSTRACT: Application of a QCL based spectrometer to cw supersonic slit jet expansions of CO and HX (X= F, Cl, CN, CCH) are reported. Spectroscopic analysis of fundamental, combination and hot bands of the CO stretching vibrations provide ro-vibrational parameters for low frequency intermolecular vibrations that can be incorporated in determination of morphed potentials for the respective dimers.
    No preview · Article · Jan 2011
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    ABSTRACT: An extended analysis of the noncovalent interaction OC:HI is reported using microwave and infrared supersonic jet spectroscopic techniques. All available spectroscopic data then provide the basis for generating an accurately determined vibrationally complete semiempirical intermolecular potential function using a four-dimensional potential coordinate morphing methodology. These results are consistent with the existence of four bound isomers: OC-HI, OC-IH, CO-HI, and CO-IH. Analysis also leads to unequivocal characterization of the common isotopic ground state as having the OC-HI structure and with the first excited state having the OC-IH structure with an energy of 3.4683(80) cm(-1) above the ground state. The potential is consistent with the following barriers between the pairs of isomers: 382(4) cm(-1) (OC-IH/OC-HI), 294(5) cm(-1) (CO-IH/CO-HI), 324(3) cm(-1) (OC-IH/CO-IH), and 301(2) cm(-1) (OC-HI/CO-HI) defined with respect to each lower minimum. The potential is also determined to have a linear OC-IH van der Waals global equilibrium minimum structure having R(e)=4.180(11) Å, θ(1)=0.00(1)°, and θ(2)=0.00(1)°. This is differentiated from its OC-HI ground state hydrogen bound structure having R(0)=4.895(1) Å, θ(1)=20.48(1)°, and θ(2)=155.213(1)° where the distances are defined between the centers of mass of the monomers and θ(1) and θ(2) as cos(-1)[<cos(2) θ(i)>(1/2)] for i=1 and 2. A fundamentally new molecular phenomenon - ground state isotopic isomerization is proposed based on the generated semiempirical potential. The protonated ground state hydrogen-bonded OC-HI structure is predicted to be converted on deuteration to the corresponding ground state van der Waals OC-ID isomeric structure. This results in a large anomalous isotope effect in which the R(0) center of mass distance between monomeric components changes from 4.895(1) to 4.286(1) Å. Such a proposed isotopic effect is demonstrated to be a consequence of differential zero point energy factors resulting from the shallower nature of hydrogen bonding at a local potential minimum (greater quartic character of the potential) relative to the corresponding van der Waals global minimum. Further consequences of this anomalous deuterium isotope effect are also discussed.
    Full-text · Article · Nov 2010 · The Journal of Chemical Physics

Publication Stats

1k Citations
246.47 Total Impact Points

Institutions

  • 1982-2015
    • Texas A&M University
      • Department of Chemistry
      College Station, Texas, United States
  • 1997-2004
    • Alabama A & M University
      Huntsville, Alabama, United States
  • 1996
    • Université de Montréal
      • Department of Physics
      Montréal, Quebec, Canada
  • 1992-1993
    • University of Exeter
      • Department of Biosciences
      Exeter, England, United Kingdom