Mixed Ramp-Gaussian Basis Sets.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Molecular orbital basis sets are crucial for accurate quantum chemical calculations.
• Traditional basis sets primarily use Gaussian functions, which can be computationally intensive.
• Developing more efficient basis sets is essential for advancing computational chemistry.

Purpose of the Study:

• To explore the use of mixed ramp-Gaussian basis sets for molecular orbital calculations.
• To demonstrate a method for efficiently computing integrals with ramp-Gaussian functions.
• To assess the performance of a new basis set, R-31+G, compared to a standard Gaussian basis set.

Main Methods:

• Modeling ramp-Gaussian products as sums of ramp functions.
• Developing algorithms for fast and accurate computation of one- and two-electron integrals.
• Constructing the R-31+G mixed basis set by replacing core functions of 6-31+G with ramps.
• Performing self-consistent Hartree-Fock calculations.

Main Results:

• A method was developed to compute integrals involving ramp-Gaussian functions efficiently.
• The R-31+G basis set was successfully constructed.
• Self-consistent Hartree-Fock calculations showed similar thermochemical predictions between R-31+G and 6-31+G.
• The R-31+G basis set demonstrated potential for significant computational speed-up.

Conclusions:

• Mixed ramp-Gaussian basis sets offer a viable alternative to purely Gaussian basis sets.
• The proposed computational approach enables faster and accurate integral calculations.
• The R-31+G basis set shows promise for accelerating quantum chemical simulations without sacrificing accuracy.