Non-adiabatic effects in quantum dynamical investigations of nuclei in the collision system H2 + H+, H + H2+ and H3+

• Applicant: Professor Dr. Ralph Jaquet
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: from 2008 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 65676567

For the system H3+ (singlet ground state) spectroscopic and scattering investigations will be performed including especially non-adiabatic effects. H3+ is the most important molecule in the field of ion-physics, plasma physics and astrophysics (history of our universe, molecular reactions in the interstellar space and on planets like Jupiter or Saturn) for which it is important to get detailed, highly accurate information about the electron-nuclei dynamics. This includes the following topics: a) bound and excited states and the continuum, b) different electron and nuclear spin states, and c) symmetry-forbidden processes. Based on our global highly accurate potential energy surfaces (PES) for the three lowest electronic states using all necessary couplings between the PESs we want to calculate first the ro-vibrational transition frequencies for the electronic ground state with an accuracy better than 0.01 cm-1. Non-adiabatic effects will be taken care of by two different strategies: (a) use of geometry-dependent effective nuclear masses for the ground state PES, and (b) coupling of several electronic PESs in diabatic or in adiabatic representation. The high accuracy should be gained at least in the ranges of the potential energy surface from the zero-point energy up to slightly below the dissociation energy (perhaps even beyond). The PESs are based on ab initio calculations using the R12 or Gaussian geminal methods, which explicitly take into account the interelectronic distance r_12 in the electronic wavefunction. Corrections to the PESs include the adiabatic and relativistic energy contributions. The non-adiabatic couplings are calculated an ab initio level, too. The same is true for the geometry-dependent nuclear mass-corrections. In the asymptotic region of the PES (region of dissociation) one finds a strong avoided crossing, which leads to couplings of singular type. For that reason, one needs for these regions a nuclear dynamics based on the coupling of several electronic PESs.The investigation of the nuclear dynamics, especially the influence of non-adiabatic effects, will be performed for the whole energy region: from the energy minimum to the region of dissociation energy (spectroscopy) and far beyond (reaction dynamics: from low (ultra-cold) to high collision energy): (a) Spectroscopic investigations from bound states up to resonances(b) Time-independent investigations of ultra-cold processes for the ortho-para conversion of H2 in collision with H+ (single PES),(c) Radiative association of H2 + H+ -> H3+ (stabilization by energy reduction via radiation),(d) Investigation of photodissociation/predissociation of H3+ around the dissociation energy, and(e) Time-dependent investigations of the charge exchange processes in the collision of H2 + H+ using coupled PESs (collision energies >1.8eV).

• DFG Programme: Research Grants