We present a complex multicon figurational self-consistent field (CMCSCF)-
based approach to investigate electron{atom/molecule scattering resonances. A modifi ed second quantization algebra adapted for biorthogonal spin orbitals has been applied
to develop a quadratically convergent CMCSCF scheme. A new step-length
control algorithm has been introduced in order to control the walk on the complex
energy hypersurface and converge to correct CMCSCF stationary point. We have
also developed a method (M1 method) based on the multiconfigurational spin tensor
electron propagator (MCSTEP) to calculate resonance energies directly.
These methods have been applied to investigate atomic and molecular scattering
resonances. The test cases for our application were 2^P Be- and 2II_g N-_2 shape
resonances. The position and the width of these resonances have been calculated for
different complete active space choices. Convergence for CMCSCF calculations to
a tolerance of 1:0 x 10^-10 a.u. for the energy gradient is achieved typically within
ten iterations or less. The wide distribution of the values for the position and the
width of the resonance reported in the literature has been explained by showing that
there actually exists two distinct resonances which are close in energy. The resonance
positions and widths from our calculation for the 2^IIg N-_2 shape resonance have been
found to be very close to the experimental results. In another study, the effect of the
orbitals with higher angular momentum has been investigated.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-05-578 |
| Date | 2009 May 1900 |
| Creators | Samanta, Kousik |
| Contributors | Yeager, Danny L. |
| Source Sets | Texas A and M University |
| Language | English |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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