Ab Initio Variational Calculations Of Molecular Vibrational Rotational Spectra

This work had its beginnings in the early 1980s at the University ofWollongong, with significant contributions from Dr. Margret Hamilton, Professors Peter G. Burton and Greg Doherty. The emphasis was to develop computer code to solve the nuclear Schrodinger problem. For bent triatomic molecules the project was fmally realized at the University of Newcastle a decade or so later, with the contribution from Ms. Feng Wan g. Aspects of this work are now taught in the quantum mechanics and electron spectroscopy courses at The University of Newcastle. Even now "complete" ab initio solutions of the time-independent SchrOdinger equation is not commonplace for molecules containing four atoms or more. In fact, when using the Eckart-Watson nuclear Hamiltonian a further restriction needs to be imposed; that is, the molecule is restricted to undergoing small amplitudes of vibration. This Hamiltonian is useful for molecules containing massive nuclei and moreover, has been extremely useful in interpreting the rovibrational spectra of small molecules. Nevertheless, a number of nuclear Hamiltonians that do not embed an equilibrium geometry have become well established and are extremely successful in interpreting rovibrational spectra of floppy molecules. Furthermore, solution algorithms vary greatly from research group to research group and it is still unclear which aspects will survive the next decade. For example, even for a triatomic molecule a general form of a potential function has not yet been uncovered that will generally interpolate with accuracy and precision ab initio discrete surfaces.

The latest in a series providing chemical physicists with a forum for critical, authoritative evaluations of advances in every area of the discipline, this stand-alone volume focuses on using high resolution molecular spectroscopy to arrive at global and accurate Vibration Hamiltonians.

This volume continues presentation of the proceedings of a NATO Advanced Research Workshop (ARW) held at Rabat, Morocco on the 17-19th of November 2005 entitled Remote Sensing of the Atmosphere for Environmental Security. Coverage includes a review of recent and upcoming experimental satellite measurements of the Earth’s atmosphere, characterisation of pollution in urban areas and the growing lack of water in many countries of the Mediterranean area, and more.

The book reviews the results of vibration-rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration-rotational spectroscopy. It shows for example that the tunneling vibration-rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states. New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops. Group theoretical analysis of floppy molecules, especially the tunneling effects in nonrigid molecules, will also be discussed. Contents:High-Resolution Spectroscopy of Transient Molecules and Its Applications to Molecular Dynamics (E Hirota & Y Endo)Vibration-Rotation Spectra of Reactive Molecules: Interplay of Ab Initio Calculations and High-Resolution Experimental Studies (H Bürger & W Thiel)Rotational Spectra of Symmetric Top Molecules: Correlation-Free Reduced Forms of Hamiltonians, Advances in Measuring Techniques, and Determination of Molecular Parameters from Experimental Data (K Sarka et al.)Hot Bands in Infrared Spectra of Symmetric Top and Some Other Molecules. A Useful Tool to Reach Hidden Information (G Graner & H Bürger)The Formation of Four-Fold Rovibrational Energy Clusters in H2S, H2Se, and H2Te (P Jensen et al.)Phase Angles in the Matrix Elements of Molecular Spectroscopy (C di Lauro & F Lattanzi)High-Resolution Infrared Spectroscopy and One-Dimensional Large Amplitude Motion in Asymmetric Tops: HNO3 and H2O2 (J-M Flaud & A Perrin)Extended Molecular Symmetry Groups: Symmetry Analysis of Molecules Consisting of Two Coaxial Rotors (P Soldán)Quantum-Mechanical Studies of Radiative Association Reactions: Formation of HeH+, NeH+ and ArH+ (W P Kraemer et al.) Readership: Chemists, astrophysicists, laser physicists and other general physicists. keywords:Transient and Reactive Molecules;Reduced Hamiltonians;Hot Bands;Rovibrational Energy Clusters;Phase Angles in Matrix Elements;Large Amplitude Vibrations;Molecular Symmetry Groups;Radiation Association Reactions

Relativistic effects are of major importance for understanding the properties of heavier atoms and molecules. Volumes I-III of Relativistic Theory of Atoms and Molecules constitute the only available bibliography on related calculations. In Volume III, 3792 new references covering 1993-1999 are added to the database. The material is characterized by an analysis of the respective papers. The volume gives the user a comprehensive bibliography on relativistic atomic and molecular calculations, including studies on the Dirac equation and related solid-state work.

The book reviews the results of vibration-rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration-rotational spectroscopy. It shows for example that the tunneling vibration-rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states. New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops. Group theoretical analysis of floppy molecules, especially the tunneling effects in nonrigid molecules, will also be discussed.

The field of High-Resolution Spectroscopy has been considerably extended and even redefined in some areas. Combining the knowledge of spectroscopy, laser technology, chemical computation, and experiments, Handbook of High-Resolution Spectroscopy provides a comprehensive survey of the whole field as it presents itself today, with emphasis on the recent developments. This essential handbook for advanced research students, graduate students, and researchers takes a systematic approach through the range of wavelengths and includes the latest advances in experiment and theory that will help and guide future applications. The first comprehensive survey in high-resolution molecular spectroscopy for over 15 years Brings together the knowledge of spectroscopy, laser technology, chemical computation and experiments Brings the reader up-to-date with the many advances that have been made in recent times Takes the reader through the range of wavelengths, covering all possible techniques such as Microwave Spectroscopy, Infrared Spectroscopy, Raman Spectroscopy, VIS, UV and VUV Combines theoretical, computational and experimental aspects Has numerous applications in a wide range of scientific domains Edited by two leaders in this field Provides an overview of rotational, vibration, electronic and photoelectron spectroscopy Volume 1 - Introduction: Fundamentals of Molecular Spectroscopy Volume 2 - High-Resolution Molecular Spectroscopy: Methods and Results Volume 3 - Special Methods & Applications

Methods in Reaction Dynamics is a collection of lectures given at the 1999 Mariapfarr Workshop in Theoretical Chemistry. Arranged as a series of detailed reviews, it provides an overview of quantum mechanical techniques used to describe and simulate the dynamics and kinetics of elementary chemical reactions. The volume provides in-depth discussions of selected topics in Theoretical Chemistry, such as quantum methods in theoretical and computational reaction dynamics and kinetics; time-dependent, time-independent and mixed quantum-classical techniques. Some of the topics have not been reviewed before in detail.