Ryan P. A. Bettens Personal Home Page

Associate Professor, Department of Chemistry, NUS.

B.Sc., 1986, University of Queensland, Australia.
Ph.D., 1992, Monash University, Australia.

Tel: (65)-6516-2846
Fax: (65)-6779-1691
Email: chmbrpa@nus.edu.sg

PAST and PRESENT GROUP MEMBERS and CO-MEMBERS

LABORATORY

Located in S7-04-05 we currently have available a 75 - 110 GHz Stark and frequency modulated microwave spectrometer.  In collaboration with Dr Leong Lai Peng, we also possess a stop-flow UV/Vis spectrometer.  The computational resources available, along with the NUS facilities, include five Sunfire X4100s (purchased along with Dr Adrian M. Lee), a DEC ALPHA XP1000 workstation and as well as numerous high-end PC workstations.

CURRENT PROGRAMME

Major Programme

Presently is entirely theoretical and computational chemistry. We are working toward the application and development of a theoretical method to accurately and efficiently calculate the energies, properties and dynamics of large molecular systems and complexes. By “accurate” we mean the theoretical method agrees well with experiment, or a low level theoretical method agrees well with a much higher level of theory.

The main thrust of our major research programme is provided in publication [41]. It has been shown recently that the total energy, and its derivatives, of a molecule can be accurately reproduced by fragmenting a molecule into smaller molecules, essentially achieving linear scaling in computing energies with molecular size. Furthermore the method is completely amenable to parallelization, additionally enhancing its efficiency. This coupled with composite methods and, in principle, PES construction of fragments means that finally we are almost at the point of being able to accurately compute energies and properties of large systems like proteins from first principles.

Furthermore, we have recently finished a study on the calculation of NMR spectra using fragmentation, and find that it works extremely well. The manuscript has been submitted and is currently under review. However, we do note some deficiencies in the method that prevents us from taking that final step in being able to apply high level ab initio calculations to proteins. It is in this area that we are now concentrating all our efforts, and that is the adequate description of intramolecular non-bonded interactions involving a significant number of monopoles. We recognize the efforts of others in this area (Li, Li and Jiang), but find that their fragmentation scheme requires very large fragment sizes for an adequate description of a protein like crambin (1CNR PDB, 642 atoms), whereby their largest fragment is fully almost one-third of the entire protein. We believe our largest fragment will not exceed one-twelfth this size for this system, and much smaller for larger proteins.

Minor Programme

Foremost is the study of the kinetics of complex reaction networks. This also includes the calculation and measurement of reaction rate coefficients. The reaction networks I’ve been involved with include interstellar chemistry, the Maillard reaction, antioxidant reactions and the highly unusual kinetic behavior of the reaction between tetrallyl tin and an aldehyde. The latter is an ongoing collaboration between my group and Griffith University in Australia with Dr David Young.

Several publications have resulted from the studies involving the calculation of rate coefficients relevant to the interstellar chemical reaction network [19, 21, 24]. Also of interest in interstellar chemistry is the observation of highly saturated species like diethyl ether [32], which can only be produced in dust clouds in star forming regions, rather than the more usual dark quiescent clouds in the interstellar medium. Is this case mm-wave spectroscopic studies are required so that deep space searches can be conduct for the species.

The ability of an antioxidant to scavenge reactive radicals depends entirely on how rapidly it is able to react with the harmful radical itself. For many antioxidants this involves a hydrogen atom abstraction from the antioxidant to the radical (often thought to be a peroxy radical). Polyphenols constitute a large class of antioxidants that behave in the above manner. Our studies have been helpful in predicting what structural properties the antioxidant must possess in order to be effective. We have investigated these structure-activity relationships both theoretically [40] and experimentally (publication is preparation), and our research in this area is still ongoing.

The Maillard reaction network is much like the interstellar chemical reaction network was in the 1970’s. Little is understood in detail, and only qualitative descriptions of the mechanism of reaction between an amino acid and sugar are available. Here, in collaboration with Dr Leong Lai Peng, we are trying to explicitly produce a reaction network, but progress is slow largely due to the incredible complexity of such a seemingly simple system. We have reduced the complexity of the system under study by considering the simplest sugar (glyceraldehyde) and amino acid (glycine), but even this system has proven to be complex. Reducing the complexity still further by substituting a primary amine (butylamine) for the amino acid and using hydroxyacetaldehyde as the “sugar” is currently ongoing. However, the first step does seem to be Schiff base formation and a so-called aldol rearrangement.

Also as part of my minor research program I make an effort to collaborate with colleagues requiring theoretical chemical calculations to aid in their main research programme. An example of this is publication [38], and various other collaborations (Zeng Huaqiang, Edward Tiekink, Richard Wong) are also on-going in wide ranging areas of chemistry.

SEMINARS

Electrostatics I

Basis Sets

CM1101 Presentations

Antibonding MOs are higher in energy than the corresponding bonding MOs are lower in energy.  See the presentation for a simple explanation.

COMPLETE PUBLICATION LIST

H Index: 17

2008

  1. “Co-crystalization os 2,2'-dithiodibenzoic acid with the isomeric n-pyridines, n = 2, 3 and 4: supramolecular polymers and the influence of steric factors upon aggretation patterns.”
    Grant A. Broker, Ryan P. A. Bettens and Edward E. R. T. Tiekink
    CrystEngComm. 10 (2008) 879 – 887.

2007

  1. “On the accurate reproduction of ab initio interaction energies between an enzyme and substrate.”
    Ryan P. A. Bettens and Adrian M. Lee
    Chem. Phys. Lett. 449 (2007) 341 – 346.
  2. “First principles NMR calculations by fragmentation.”
    Adrian M. Lee and Ryan P. A. Bettens
    J. Phys. Chem. A 111 (2007) 5111 – 5115.
  3. "The conformers of hydroxyacetaldehyde."
    Yanping Fan, Lai Peng Leong and Ryan P. A. Bettens
    J. Phys. Chem. A 111 (2007) 5081 – 5085.

2006

  1. “A new algorithm for molecular fragmentation in quantum chemical calculations.”
    Ryan P. A. Bettens and Adrian M. Lee
    J. Phys. Chem. A 110 (2006) 8777 – 8785.
  2. “Investigation of the influence of hydroxy groups on the radical scavenging ability of polyphenols.”
    Thavasi V, Leong Lai Peng, Ryan P. A. Bettens
    J. Phys. Chem. A 110 (2006) 4918 – 4923.
  3. “Approximating coupled cluster level vibrational frequencies with composite methods.”
    Yanping Fan, Junming Ho and Ryan P. A. Bettens
    J. Phys. Chem. A 110 (2006) 2796 – 2800.

2005

  1. “Prevalence of the thioamide {…H–N–C=S}2 synthon - solid-state (X-ray crystallography), solution (NMR) and gas-phase (theoretical) structures of O-methyl-N-aryl-thiocarbamides. ”
    Soo Yei Ho, Ryan P. A. Bettens, Dainis Dakternieks, Andrew Duthieb and Edward R. T. Tiek
    Cryst. Eng. Comm. 7 (2005) 682 – 689.
  2. “Millimeter and submillimeter wave rotational spectrum of pyridine in the ground and excited vibrational states.”
    Enyi Ye, Ryan P.A. Bettens, Frank C. De Lucia, Douglas T. Petkie and Sieghard Albert
    J. Mol. Spectrosc. 232 (2005) 61 – 65.
  3. “Millimeter wave measurement and assignment of the rotational spectrum of aniline.”
    Enyi Ye, Krishnan Chandrasekaran and Ryan P.A. Bettens
    J. Mol. Spectrosc. 229 (2005) 54 – 56.

2004

  1. “Comparison of fundamental and harmonic frequencies of first-row closed-shell diatomics calculated using fully ab initio methods and composite methods.”
    Ryan P. A. Bettens
    J. Phys. Chem. A 108 (2004) 1826 – 1829.
  2. “Millimeter wave measurement and assignment of the rotational spectrum of 2-aminopyridine.”
    Enyi Ye and Ryan P.A. Bettens
    J. Mol. Spectrosc. 223 (2004) 73 – 79.

2003

  1. "Bound state potential energy surface construction: Ab initio zero-point energies and vibrationally averaged rotational constants."
    Ryan P. A. Bettens
    J. Am. Chem. Soc. 125 (2003) 584 – 587.
  2. “The millimetre-wave and sub millimetre-wave spectrum of the trans-trans conformer of diethylether (C2H5OC2H5).”
    Ivan Medvedev, Manfred Winnewisser, Frank C. De Lucia, Eric Herbst, Ye Enyi, Ryan P. A. Bettens, Ewa Bialkowska-Jaworskq, Oleksander Desyatnyk, Lech Pszczolkowski, and Zbigniew Kisiel.
    Astrophys. J. Supp. 148 (2003) 593 - 597.

2002

  1. "Multiple surface long-range interaction potentials between C (3Pj) and closed-shell molecules."
    Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 116 (2002) 101 – 104.

2001

  1. "Capture rates for collisions of C (3Pj) and Ge (1S0) with unsaturated hydrocarbons."
    Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 114 (2001) 10342 – 10354.
  2. "Interpolated potential-energy surface and reaction dynamics for BH+ + H2."
    Rebecca O. Fuller, Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 114 (2001) 10711 – 10716.

2000

  1. "The microwave spectrum, structure, and ring-puckering of the cyclic dipeptide diketopiperazine."
    Fiona L. Bettens, Ryan P. A. Bettens, Ronald D. Brown and Peter D. Godfrey
    J. Am. Chem. Soc. 122 (2000) 5856 – 5860.
  2. "Ab initio potential energy surface for the reactions between H2O and H."
    Ryan P. A. Bettens, Michael A. Collins, Meredith J. T. Jordan and Dong H. Zhang
    J. Chem. Phys. 122 (2000) 10162 – 10172.
  3. "Large molecules in the envelope surrounding IRC+10216."
    Thomas J. Millar, Eric Herbst and Ryan P. A. Bettens
    Mon. Not. R. astron. Soc. 316 (2000) 195 – 203.

1999

  1. "The abundance of C7- in diffuse clouds. "
    Deborah P Ruffle, R. P. A. Bettens; Radoslava Terzieva and Herbst, Eric
    Ap. J. 523 (1999) 678 – 682.
  2. "Interpolated potential energy surface and reaction dynamics for O(3P) + H3+ (1A1') and OH+ (3S-) + H2(1Sg+)."
    Ryan P. A. Bettens, Trevor A. Hansen and Michael A. Collins
    J. Chem. Phys. 111 (1999) 6322 – 6332.
  3. "Learning to interpolate molecular potential energy surfaces with confidence: A Bayesian approach."
    Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 111 (1999) 816 – 826.
  4. "Potential energy surface for the reactions BeH2 + H = BeH + H2."
    Michael A. Collins and Ryan P. A. Bettens
    Phys. Chem. Chem. Phys. 1 (1999) 939 – 945.

1998

  1. “Interpolated potential energy surface and dynamics for the reactions between N(4S) and H3+(1A1').”
    Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 109 (1998) 9728 – 9736.
  2. “ FASSST: A new gas-phase analytical tool.”
    Sieghard Albert , Douglas T. Petkie , Ryan P. A. Bettens, S. P. Belov and Frank C. De Lucia
    Analytical Chem. 70 (1998) 719A-727A
  3. “Potential energy surfaces and dynamics for the reactions between C(3P) and H3+(1A1').”
    Ryan P. A. Bettens and Michael A. Collins
    J. Chem. Phys. 108 (1998) 2424 – 2433.

1997

  1. “A fast scan submillimeter spectroscopic technique.”
    Douglas T. Petkie, Thomas M. Goyette, Ryan P. A. Bettens, S. P. Belov, Sieghard Albert, Paul Helminger and Frank C. De Lucia
    Rev. Sci. Instrum. 68 (1997) 1675 – 1683.
  2. “The formation of large hydrocarbons and carbon clusters in dense interstellar clouds.”
    Ap. J. 478 (1997) 585 – 593

1996

  1. “Fractional abundances of molecules in dense interstellar clouds: A compendium of recent model results.”
    HH Lee, Ryan P. A. Bettens and Eric Herbst
    Ap. J. Supp. 119 (1996) 111 – 114.
  2. “The abundance of very large hydrocarbons and carbon clusters in the diffuse interstellar medium.”
    Ryan P. A. Bettens and Eric Herbst
    Ap. J. 468 (1996) 686 – 693.

1995

  1. “The interstellar gas-phase production of highly complex hydrocarbons - construction of a model.”
    Ryan P. A. Bettens and Eric Herbst
    Int. J. Mass Spectrom. 149 (1995) 321 – 343.
  2. “Intermolecular force-field and approximate equilibrium structure of various complexes containing one or 2 rare-gas atoms from microwave spectroscopic constants.”
    Ryan P. A. Bettens, R. M. Spycher and Alfred Bauder
    Mol. Phys. 86 (1995) 487 – 511.
  3. “The importance of classes of neutral-neutral reactions in the production of complex interstellar-molecules.”
    Ryan P. A. Bettens, HH Lee and Eric Herbst
    Ap. J. 443 (1995) 664 – 674.
  4. “The microwave-spectrum and structure of the pyridine-CO complex.”
    Ryan P. A. Bettens and Alfred Bauder
    J. Chem. Phys. 102 (1995) 1501 – 1509.

1994

  1. “A microwave study and centrifugal-distortion analysis of the pyrrole-CO complex.”
    Ryan P. A. Bettens, Sonya R Huber and Alfred Bauder
    J. Phys. Chem. 98 (1994) 4551 – 4563.

1993

  1. “Ion-molecule chemistry of HnC3O+, C3O2+, and C3O+.”
    Simon Petrie, Ryan P. A. Bettens, Colin G. Freeman and Muray J. McEwan
    J. Phys. Chem. 97 (1993) 13673 – 13676.
  2. “ The ion chemistry of HnC3O+, C3O2+ and C3O+ in dense interstellar clouds - an experimental-study.”
    Simon Petrie, Ryan P. A. Bettens, Colin G. Freeman and Muray J. McEwan
    Mon. Not. R. Astron. Soc. 264 (1993) 862 – 864.
  3. “ Line strengths of methanol by the internal axis method.”
    Dinah M. Cragg, M. A. Mekhtiev, Ryan P. A. Betttens, Peter D. Godfrey and Ronald D. Brown.
    Mon. Not. R. Astron. Soc. 264 (1993) 769 – 772.
  4. “Interstellar chemistry and the tight far-infrared radio correlation.”
    Ryan P. A. Betttens , Ronald D. Brown , Dinah M. Cragg, Clive J Dickinson and Peter D. Godfrey
    Mon. Not. R. Astron. Soc. 263 (1993) 93 – 97.

1992

  1. “Interstellar Chemistry - oxygen and its influence on complex molecule formation and complex-molecules containing oxygen in dark clouds.”
    Ryan P. A. Bettens and Ronald D. Brown
    Mon. Not. R. Astron. Soc. 258 (1992) 347 – 359.
  2. “The gas-phase chemical evolution of dark clouds.”
    Ryan P. A. Bettens
    Aust. J. Physics 45 (1992) 451 – 461.
  3. “The microwave-spectrum and the molecular-structure of bromochlorodifluoromethane (BCF).”
    Ryan P. A. Bettens and Ronald D. Brown
    J. Mol. Spectrosc. 155 (1992) 55-76.

1990

  1. “Interstellar Chemistry - hot-ion reactions.”
    Ryan P. A. Bettens, Dinah M. Cragg and Ronald D. Brown
    Mon. Not. R. Astron. Soc. 245 (1990) 623 – 636.

1987

  1. “The dipole moment of C3H2.”
    Ronald D. Brown, Peter D. Godfrey and Ryan P. A. Bettens
    Mon. Not. R. Astron. Soc. 227 (1987) P19 – P20.
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Last modified: 22nd August 2008