Efficient EOM-CC-based Protocol for the Calculation of Electron Affinity of Solvated Nucleobases: Uracil as a Case...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Biophysical Chemistry

Background:

• Accurate calculation of electron affinity for nucleobases is crucial for understanding their chemical properties.
• Previous methods struggled with explicit solvation effects, leading to inaccuracies.

Purpose of the Study:

• To present a novel explicit solvation protocol for calculating electron affinity values of solvated nucleobases.
• To investigate the impact of solvation on electron affinity and assess the reliability of the new method.

Main Methods:

• Employed a quantum mechanics/molecular mechanics (QM/MM) approach.
• Utilized the domain-based pair natural orbital equation-of-motion coupled-cluster single-double (DPI-EOM-CCSD) method.
• Analyzed the sensitivity of electron affinity to solvation parameters like water molecule distribution and basis set size.

Main Results:

• Electron affinity values are sensitive to the local water distribution and convergence requires careful consideration of snapshots and water box size.
• Nonpolarizable water models overestimate electron affinity and introduce sensitivity to the QM region size.
• Calculated adiabatic electron affinity values show excellent agreement with experimental results.

Conclusions:

• The developed QM/MM protocol provides a controllable and accurate method for calculating electron affinity of solvated nucleobases.
• The study highlights the importance of explicit solvation and appropriate computational choices for reliable electron affinity predictions.