Basis sets for transition metals: Optimized outer p functions.

Area of Science:

• Quantum Chemistry
• Computational Chemistry

Background:

• The (n + 1)p orbital, though unoccupied in transition metal ground states, is vital for their complex structures.
• Standard methods of adding diffuse functions to basis sets often fail to achieve the correct orbital energy due to node placement issues.

Purpose of the Study:

• To develop and present a set of optimized (n + 1)p functions for improved accuracy in transition metal complex calculations.
• To address the deficiencies in standard basis sets regarding the placement of the (n + 1)p orbital node.

Main Methods:

• Development of a new set of optimized (n + 1)p basis functions.
• Testing the performance of these new functions against standard and fully uncontracted basis sets.
• Analysis of orbital energy and node placement accuracy.

Main Results:

• The newly optimized (n + 1)p functions provide a more compact and satisfactory solution for node placement compared to standard diffuse functions.
• These optimized functions demonstrate improved performance, comparable to fully uncontracted basis sets, in calculations involving transition metal complexes.
• Common deficiencies in typical and standard basis sets (e.g., GAUSSIAN94) were identified and addressed.

Conclusions:

• Optimized (n + 1)p functions are essential for accurate modeling of transition metal complexes.
• The proposed functions offer a superior and more efficient alternative to existing methods for improving basis set accuracy.