Potential Energy Curves and Generalized Oscillator Strength for Doubly Excited States of the Hydrogen Molecule

L O Santos,R F Nascimento,A B Rochaz,N V De Castro Faria,Ginette Jalbert

doi:10.1088/1742-6596/635/7/072087

Abstract

SynopsisIn this work we report calculations of potential energy curves in the 1.2a.u. ≤ R ≤ 100a.u. range at the Multireference Configuration Interaction (MRCI) level for doubly excited states of the H2 molecule. The molecular state which dissociates into two H(2s) atoms is clearly identified. The Generalized Oscillator Strength as a function of transferred momentum for three doubly excited states is also presented.

Highlights

One of the first evidences of the autoionized doubly excited states of H2 was obtained in the experiment of Crowe and McConkey in 1973 [1] in which electrons collided with H2 at impact energies of 29, 33, 50, 100 and 399 eV
We present our results for the potential curves of Q2 states from the Frank-Condon region (1.2a.u. ≤ R ≤ 3.0.a.u.) to the dissociative region (≈ 100a.u.) as the Generalized Oscillator Strength, within the vertical approximation, using the Multireference Configuration Interaction (MRCI) [10]
In order to test the quality of our wavefunction, we have calculated the dipole moment of the H2 molecule and show in Table 1 the results for the excited states B1Σ+u and B′1Σ+u, respectively

Summary

Introduction

One of the first evidences of the autoionized doubly excited states of H2 was obtained in the experiment of Crowe and McConkey in 1973 [1] in which electrons collided with H2 at impact energies of 29, 33, 50, 100 and 399 eV. Using different techniques to solve for each internuclear distance region and taking special care of intermediate distances in order to connect the different regimes in which calculations were done, they were able to calculate potential energy curves from 3 a.u. to 200 a.u. Recently our experimental group [6] observed the pair H(2s) + H(2s) by measuring neutral fragments in coincidence after H2 dissociation induced by electron impact, confirming for the first time the existence of such states. Since we intend to work with our experimental group [6], is desirable to provide it with cross section calculations within the First Born Approximation, that would be helpful in the experimental apparatus adjustment For this purpose, we begin by presenting Generalized Oscillator Strength calculation for some doubly excited states. It is important to note that the main feature of our calculations is to provide for the first time an unambiguous characterization of the electronic state that goes, in the dissociation limit, to H(2s) + H(2s) fragments

Objectives

Results

Conclusion