Behavior of the Position-Spread Tensor in Diatomic Systems

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Molecular Physics

Background:

• The Position-Spread Tensor (Λ) is the second moment cumulant of the position operator.
• It is an intrinsic, additive property of molecules, invariant to translation and rotation (trace).

Purpose of the Study:

• Investigate the behavior of the Position-Spread Tensor (Λ) in light diatomic molecules (neutral and ionic).
• Analyze the sensitivity of Λ to molecular wave function reorganization and electron mobility.

Main Methods:

• Full Configuration Interaction (FCI) calculations.
• Examination of the longitudinal (Λ∥) and transversal (Λ⊥) components of the tensor.

Main Results:

• Λ∥ increases with bond stretching, peaks at bond breaking, then decreases to atomic values.
• Λ⊥ components monotonically increase towards atomic values.
• Position Spread is highly sensitive to wave function changes, e.g., neutral-ionic avoided crossing in LiF.

Conclusions:

• The Position Spread is a valuable descriptor of molecular wave function characteristics.
• Its behavior provides insights into bond dynamics and electronic properties.