Correlated wavefunction methods in bioinorganic chemistry.

Area of Science:

• Computational chemistry
• Inorganic chemistry
• Biophysical chemistry

Background:

• Wavefunction-based ab initio methods are crucial for studying transition metal complexes.
• Challenges exist in applying these methods to open-shell systems relevant to bioinorganic chemistry.

Purpose of the Study:

• To highlight challenges in applying ab initio methods to transition metal complexes.
• To emphasize the importance of reference wavefunction generation.
• To illustrate the interplay of relativistic and correlation effects.

Main Methods:

• Discussion of single-reference and multireference wavefunction-based ab initio methods.
• Application of coupled-cluster theory.
• Analysis of relativistic and correlation effects.

Main Results:

• Erroneous results can be obtained with coupled-cluster theory if the reference wavefunction is not properly handled, as shown for iron(IV)-oxo complexes.
• Relativistic effects significantly influence the relative stabilities of different species in dinuclear copper models.

Conclusions:

• The generation and nature of the reference wavefunction are critical for accurate ab initio calculations on transition metal complexes.
• Understanding the interplay between relativistic and correlation effects is essential for studying systems like copper active sites.