Accurate basis set truncation for wavefunction embedding.

Area of Science:

• Computational chemistry
• Electronic structure theory
• Quantum chemistry

Background:

• Density Functional Theory (DFT) offers an exact framework for embedded subsystem calculations.
• Truncating atomic orbital basis sets is crucial for computational efficiency in large systems.
• Existing methods may lack systematic control over basis set truncation errors.

Purpose of the Study:

• To extend projection-based embedding methods for systematic basis set truncation in DFT.
• To enable accurate and efficient electronic structure calculations for embedded subsystems.
• To provide a pathway for improving approximate kinetic energy functionals in DFT embedding.

Main Methods:

• Extension of a projection-based embedding method.
• Systematic truncation of the atomic orbital basis set for the embedded subsystem.
• Application to covalently and non-covalently bound systems (water clusters, polypeptide chains).

Main Results:

• Demonstrated controllable errors within chemical accuracy for basis set truncation.
• Successfully applied to diverse chemical systems.
• Showcased the ability to switch between accurate projection-based embedding and DFT embedding with approximate kinetic energy functionals.

Conclusions:

• The developed method allows for accurate and efficient basis set truncation in embedded DFT calculations.
• This approach offers a systematic improvement over existing approximate kinetic energy functionals in DFT embedding.
• The findings are applicable to complex molecular systems, advancing computational chemistry accuracy and efficiency.