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Howard S. Taylor

Emeritus Professor

Ph.D., 1959, University of California at Berkeley
B.A., 1956, Columbia University
Office: SSC 704
Phone: (213) 740-4112
Fax: (213) 740-8348
Email: taylor@usc.edu
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Research Focus

 
For many years, Professor Taylor's research has been on a variety of theoretical problems, generally grouped under the title of chemical, atomic, molecular, and electron dynamics.

Professor Taylor's solutions to these problems are always very original and intuitive and have resulted in his group being a center for visitors from all over the world. Visiting scientists and postdocs have come from Poland, Yugoslavia, China, France, Italy, Israel, Japan, Great Britain, India, Germany, Hungary and, of course, the United States and Canada. The interaction of these people with the graduate students give the group a very dynamic flavor and a world view. Professor Taylor's approach has always been that of a chemist, in that an intuitive physical model is first developed, followed by calculations to test these ideas. This approach has led to many advances in the field of theoretical chemistry, such as (i) the development of the stabilization method for computing the properties of short lived species, (ii) the many-body theory of electron scattering, (iii) the Hose-Taylor view of and methodology for studying quasiperiodic and chaotic phenomena, (iv) the development of methods to extract dynamics from complex experimental spectra, (v) a new stabilization method of computing all properties of scattering and chemical reactions and (vi) new signal processing methodologies that extract more information than previously available from experiment and which make certain theoretical chemical problems as diagonalization of large dense matrices and as the calculation of time correlation functions, easier to carry out.

A project of great importance now being researched is aimed at determining and understanding what quantum chaos is and how these ideas can be used to extract chemical information from complex spectra of specific atoms and molecules in and out of strong fields. Recently, a great success was enjoyed when the extraordinary complex spectra (SEP) involving the high excitation of the bending modes of acetylene was fully interpreted up to the isomerization barrier. Working from the observed energy levels and using new theoretical ideas from the convergence of Quantum Mechanics and Classical non-linear dynamics, four basic molecular motions were found that when quantized each gave rise to a simple sequence of levels. These simple sequences overlapped yielding a complex spectra. Similar analysis give simple explanations for the complex spectra of CHFClBr and N2O. Work is now continuing in which these ideas are being applied to the complex spectra of other molecules as HO2  and H3+.

Another second key project deals with new and advanced methods of signal processing aimed at extracting more information than the now used Fourier Transform analysis from time signals measured in experiments as FTNMR, FTICR, FTIR, etc. This project could have huge payoffs in knowledge gained and in funds saved in designing more sensitive instruments only to see what we now see with our new processing methods. The mathematical methods of signal processing are also being used to solve computational problems in chemistry and physics. New and powerful diagonalization techniques have been devised as have methods to obtain theoretical spectra semiclassically.

Selected publications

 
1. Semi-Classical Quantization by Padé Approximant of Periodic Orbit Sums, with J. Main, P.A. Dando, D. Belkic, Europhys. Lett., 48(3), 250-256 (1999).
2. Decimated Signal Diagonalization for Obtaining the Complete Eigenspectra of Large Matrices, D. Belkic, P.A. Dando H.S. Taylor, and J. Main, Chem. Phys. Lett., 315, 135-139 (1999).
3. Decimation and Harmonic Inversion of Periodic Orbit Signals, J. Main, P.A. Dando, D. Belkic and H.S. Taylor, J. Phys. A Math. Gen., 33, 1247-1263 (2000).
4. Decimated Signal Diagonalization for Fourier Transform Spectrometry, D. Belkic, P.A. Dando, J. Main, H.S. Taylor and S.-K. Shin, J. Phys. Chem. A, 104, 11677-11684 (2000).
5. Three Novel High-Resolution Nonlinear Methods for Fast Signal Processing, Dz. Belkic, P. A. Dando, J. Main, and H.S. Taylor, J. Chem. Phys., 113, 6542 (2000)
6. The Acetylene Bending spectrum at ~10,000 cm-1:  Quantum Assignment in the Midst of Classical Chaos, C. Jung, M. Jacobson and H.S. Taylor, J. Phys. Chem. A, 105, 681 (2001).
7. Extracting the CH Chromophore Vibrational Dynamics of CHBrClF Directly from Spectra: Unexpected Constants of the Motion and Symmetries, C. Jung, E. Ziemniak and H.S. Taylor, J. Chem. Phys., 115, 2449 (2001).
8. Semiclassical Assignment of the Vibrational Spectrum of N2O, H. Waalkens, C.Jung and H.S. Taylor, 106, 911-924 (2002).
9. Extraction of the Vibrational Dynamics from Spectra of Highly Excited Polyatomics: DCO, C. Jung, H.S. Taylor and E. Atilgan, J. Phys. Chem. A.,  106, 3092-3101 (2002).

 

Chemistry Dept., USC College of Letters, Arts & Sciences