Benchmarking the Electron Affinity of Uracil.

Area of Science:

• Quantum chemistry
• Computational physics
• Biomolecular science

Background:

• Electron attachment to nucleobases is crucial for understanding DNA/RNA damage.
• Accurate theoretical prediction of electron affinity is challenging.

Purpose of the Study:

• To accurately determine the adiabatic electron affinity (AEA) of uracil.
• To benchmark high-level computational methods for electron attachment studies on nucleobases.

Main Methods:

• Weizmann Bruecker doubles composite (W1BD) method with large basis sets (augh-cc-pVQZ+2df).
• Comparison with other high-level methods like CASPT2 and G4 theory.
• Evaluation of Density Functional Theory (DFT) methods, including M06-2X.

Main Results:

• The W1BD method predicts a positive AEA for uracil.
• The most reliable AEA value for uracil is 0.024 ± 0.013 eV.
• Hartree-Fock and MP2 methods significantly underestimate the AEA, while DFT methods like M06-2X show promise.

Conclusions:

• The W1BD method provides accurate predictions for electron attachment to uracil.
• M06-2X is a promising DFT method for studying electron-DNA/RNA interactions.
• Standard methods like Hartree-Fock and MP2 are unsuitable for this type of study.