Molecular photoionization cross sections in electron propagator theory: angular distributions beyond the dipole...

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics

Background:

• The dipole approximation is standard for photoionization studies.
• Higher-order multipole terms are often neglected but can be significant.

Purpose of the Study:

• To investigate corrections to the dipole approximation in photoionization of first-row hydrides.
• To assess the impact of electric quadrupole and magnetic dipole terms.

Main Methods:

• Calculated Dyson orbitals using ab initio electron propagator theory.
• Applied the full multipole expansion for incident photon representation.
• Estimated the importance of first-order and higher-order corrections.

Main Results:

• Corrections to the dipole approximation were quantified.
• The significance of multipole corrections varies with photon energy.
• Dyson orbital characteristics influence multipole correction magnitude.

Conclusions:

• Multipole corrections are essential for accurate photoionization angular distributions.
• Photon energy and molecular electronic structure determine the necessity of these corrections.