Ab initio rotation-vibration energy levels of triatomics to spectroscopic accuracy.
The factors that need to be taken into account to achieve spectroscopic accuracy for triatomic molecules are considered focusing on H3+ and water as examples. The magnitude of the adiabatic and non-adiabatic corrections to the Born-Oppenheimer approximation is illustrated for both molecules, and methods of including them ab initio are discussed. Electronic relativistic effects are not important for H3+, but are for water for which the magnitude of the various effects is discussed. For H3+ inclusion of rotational non-adiabatic effects means that levels can be generated to an accuracy approaching 0.01 cm(-1); for water the error is still dominated by the error in the correlation energy in the electronic structure calculation. Prospects for improving this aspect of the calculation are discussed.
Tennyson
Jonathan
J
Department of Physics and Astronomy, University College London, UK. j.tennyson@ucl.ac.uk
Barletta
Paolo
P
Kostin
Maxim A
MA
Polyansky
Oleg L
OL
Zobov
Nikolai F
NF
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004583:Electrons; D006859:Hydrogen / Q000737:chemistry; D007700:Kinetics; D008962:Models, Theoretical; D015203:Reproducibility of Results; D013055:Spectrophotometry, Infrared / Q000379:methods*; D014732:Vibration; D014867:Water / Q000737:chemistry
D014867:Water; D006859:Hydrogen