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Rydberg States (rydberg + states)
Selected AbstractsRydberg states of the helium atomINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2009Jia Deng Abstract Using the recently introduced maximum overlap method and Hartree,Fock Perturbation Theory (HFPT), we compute Hartree,Fock (HF) wavefunctions for triplet 1s ns states of the helium atom. Comparison with near-exact results from Nakatsuji's free ICI method reveals that HF theory provides a simple route to accurate energies of these Rydberg states, especially for large n. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Resonances and pseudoresonances in a potential with attractive coulomb tail: A study using analytic-continuation techniquesINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2003Imke B. Müller Abstract The performance of the complex absorbing potential (CAP) and the complex scaling (CS) methods in the detection and calculation of complex Siegert energies is studied using a 1-D long-range attractive model potential. This potential is constructed to mimic molecular properties, in particular an attractive Coulombic term, to allow one to draw conclusions on molecular ab initio studies. Analyzing the spectrum of the model potential, one compact bound state embedded in the manifold of Rydberg states is found that shows artificial resonance characteristics when applying the CAP and the CS methods. This pseudoresonance problem is less pronounced in the calculation using the CS method than in that using the CAP method. Despite this deficiency, the CAP method is shown to possess advantages over CS when dealing with physical resonances under conditions that simulate the application of standard basis sets in ab initio calculations. The accuracy of the Siegert energy is shown to be maintained when applying a subspace projection technique to the CAP method. This technique reduces the computational demand significantly and leads to an important improvement of the CAP method, which should be of particular significance in molecular applications. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 [source] Photoabsorption processes in nitrous oxide and formaldehydeINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4-5 2001I. Martín Abstract Absorption oscillator strengths and photoionization cross sections for electronic transitions involving Rydberg states that are relevant to the photochemistry of N2O and H2CO are reported. These compounds have been found to play an important role in the evolution of Earth's upper atmosphere. However, the difficulties encoutered in both laboratory measurements and theoretical calculations on the photoabsorption of these compounds are responsible for the scarcity of data in the literature. The present calculations have been performed with the molecular-adapted quantum defect orbital (MQDO) method, of which the adequacy for this type of studies has recently been assessed. A comparative analysis of the photoabsorption intensities in the molecules and their constituting atoms has enabled us to predict the variation of the extent of atomic character of the molecular Rydberg orbitals with the degree of excitation. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 [source] A theoretical investigation of the excited states of OCLO radical, cation, and anion using the CASSCF/CASPT2 methodJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2007Zi-Zhang Wei Abstract Using the complete active space self-consistent field method with a large atomic natural orbital basis set, 10, 13, and 9 electronic states of the OClO radical, OClO+ cation, and OClO, anion were calculated, respectively. Taking the further correlation effects into account, the second-order perturbation (CASPT2) calculations were carried out for the energetic calibration. The photoelectron spectroscopy of the OClO radical and OClO, anion were extensively studied in the both case of the adiabatic and vertical ionization energies. The calculated results presented the relatively complete assignment of the photoelectron bands of the experiments for OClO and its anion. Furthermore, the Rydberg states of the OClO radical were investigated by using multiconfigurational CASPT2 (MS-CASPT2) theory under the basis set of large atomic natural orbital functions augmented with an adapted 1s1p1d Rydberg functions that have specially been built for this study. Sixteen Rydberg states were obtained and the results were consistent with the experimental results. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 467,477, 2007 [source] Ultrafast Dynamics of o -Bromofluorobenzene Studied by Time-Resolved Photoelectron ImagingCHEMPHYSCHEM, Issue 8 2009Zhen-Zhou Cao Abstract Photodissociation dynamics and rotational wave packet coherences of o -bromofluorobenzene are studied by femtosecond time-resolved photoelectron imaging (see figure). The decay of different photoelectron rings shows the population decay of states from which the lifetimes of different states are determined. The variation of photoelectron angular distributions reflects the evolution of rotational coherences. Photodissociation dynamics and rotational wave packet coherences of o -bromofluorobenzene are studied by femtosecond time-resolved photoelectron imaging (TR-PEI) spectroscopy combined with the (1+2,) resonance-enhanced multiphoton ionization (REMPI). Photoelectron kinetic energy and angular distributions indicate ionization dynamics from some Rydberg states at the (1+1,) photon energy. The lifetimes of the S1 (A,) and T2 (A,) states are determined from the decay of the photoelectron signals to be 38 ps and 27 ps. The electron population decay of the two states is attributed to predissociation and tunneling dissociation. The variation of time-dependent anisotropy parameters in the first 5 ps shows the rotational wave coherences of molecule. [source] | ||||||||||