Transcorrelated methods applied to second row elements.

Area of Science:

• Quantum chemistry
• Computational physics
• Atomic and molecular science

Background:

• Accurate calculation of electronic structure is crucial for understanding chemical properties.
• Traditional methods face challenges in achieving chemical accuracy efficiently, especially for heavier elements.
• Basis set convergence remains a significant hurdle in high-accuracy quantum chemical calculations.

Purpose of the Study:

• To assess the effectiveness of the transcorrelated method for second-row elements.
• To investigate the impact of basis set choice on accuracy and convergence.
• To compare transcorrelated results with established quantum chemical techniques.

Main Methods:

• Application of transcorrelated Hamiltonians.
• Utilizing full configuration interaction quantum Monte Carlo (FCIQMC) and coupled cluster (CC) methods.
• Systematic variation of basis set size and type (e.g., cc-pVTZ).

Main Results:

• Transcorrelated method demonstrates applicability to second-row elements.
• Accelerated convergence to the complete basis set (CBS) limit is observed compared to conventional methods.
• Chemically accurate total energies and ionization potentials are achievable with the cc-pVTZ basis set.
• The use of a frozen core approximation (frozen Ne) is validated.

Conclusions:

• The transcorrelated method provides a computationally efficient pathway to high-accuracy electronic structure calculations for second-row elements.
• Basis set selection, particularly cc-pVTZ, is critical for achieving chemical accuracy.
• The approach offers a significant advantage in accelerating convergence, reducing the computational cost for reaching the CBS limit.