Research Projects

In this proposal we seek to extend our earlier project work on electron collision with carbon monoxide molecule and do systematic study on other molecular species of fundamental and practical interest. In particular, in this project we would like to investigate presence of higher lying and high spin resonant anionic states of small molecules that might give rise to long lived anions. While there are huge amount of experimental and theoretical literature available on studies related to low lying shape and Feshbach resonant states of certain molecules, studies on high lying and high spin resonant states are extremely rare. As for experimental evidence, long lived resonant anions of CO- and N2-, having lifetimes of a few microseconds, have been observed in mass spectrometer; this has generated interest in their study in past. It has been argued that high spin (quartet and sextet) states of these anions containing several equivalent electrons contribute to their longevity. This has been explained on the basis of bound state calculations of their potential energy curves of these high spin electronic states in place of proper scattering calculations. In light of the above situation here we propose to undertake high accuracy scattering calculations using R-matrix method to do systematic investigation of molecules that are computationally manageable. We plan to start with molecules having fewer electrons so that a larger active space in terms of number of electrons and virtual molecular orbitals (MO) can be used to represent both the target and scattering system. In fact, it would be necessary to include more number of virtual MOs in order to get sufficient number of high spin configurations for variational calculations. After doing preliminary fixed-nuclei calculations and upon getting convergent results (in terms of resonance parameters and cross sections) of publication quality at the equilibrium geometry we plan to do scattering calculations as a function of bond distance. Repetition of R-matrix calculations for each bond length is cumbersome and prone to make errors in preparing the input. We have developed a set of scripts that will automatically generate input and perform calculations for each molecular geometry. This is a significant development in my part and will greatly save us time to get results. Finally, cross sections for dissociative electron attachment (DEA) and vibrational excitation (VE) of the molecule will be calculated using time-dependent wave packet (TDWP) method under the local complex potential (LCP) approximation. The results of the above mentioned work will be published in reputed international journals. We have all the expertise required to complete the project. A project associate will be required who will learn and do the necessary work. A Linux workstation and MOLPRO license for the machine will also be required. We will use UK molecular R-matrix codes for scattering calculations and our own codes for TDWP calculations.

Electron-molecule collision, R-matrix method, long-lived resonances, potential energy curves, TDWP method, DEA and VE cross sections