Simple and efficient LCAO basis sets for the diffuse states in carbon nanostructures.

Area of Science:

• Computational materials science
• Quantum chemistry
• Condensed matter physics

Background:

• Accurately describing electronic states in carbon nanostructures is crucial for understanding their properties.
• Traditional methods using minimal basis sets often struggle to capture diffuse electronic states.

Purpose of the Study:

• To introduce a simplified, minimal basis set for density functional theory (DFT) calculations.
• To accurately describe the lowest unoccupied diffuse states in carbon nanostructures.

Main Methods:

• Utilized a minimal linear combination of atomic orbitals (LCAO) basis set.
• Incorporated long-range Bessel functions as additional basis functions.
• Compared results with plane-wave basis calculations for validation.

Main Results:

• The proposed minimal LCAO basis set effectively captures diffuse states in both planar sp2 (graphene) and curved carbon (C60).
• Adding long-range Bessel functions maintains a minimal basis size while improving accuracy.
• The new basis set is simpler and smaller than standard pseudo-atomic orbitals (PAOs) with polarization orbitals.

Conclusions:

• A computationally efficient and accurate method for describing diffuse states in carbon nanostructures has been established.
• This approach offers a practical alternative for DFT calculations involving these materials.