Exploration of H2 binding to the [NiFe]-hydrogenase active site with multiconfigurational density functional theory

TL;DR

This study uses a hybrid multiconfigurational DFT method to analyze H2 binding in [NiFe] hydrogenase, achieving comparable accuracy to advanced methods with less computational cost, aiding bio-inorganic reaction mechanism studies.

Contribution

The paper demonstrates that CAS-srDFT provides accurate insights into bio-inorganic systems with smaller active spaces, improving computational efficiency over traditional methods.

Findings

H2 prefers binding to Ni over Fe, consistent with previous studies.

CAS-srDFT achieves accuracy comparable to CC and DMRG methods.

Smaller active spaces in CAS-srDFT enhance computational efficiency.

Abstract

The combination of density functional theory (DFT) with a multiconfigurational wave function is an efficient way to include dynamical correlation in calculations with multiconfiguration self-consistent field wave functions. These methods can potentially be employed to elucidate reaction mechanisms in bio-inorganic chemistry, where many other methods become either too computationally expensive or too inaccurate. In this paper, a complete active space (CAS) short-range DFT (CAS-srDFT) hybrid was employed to investigate a bio-inorganic system, namely H2 binding to the active site of [NiFe] hydrogenase. This system was previously investigated with coupled-cluster (CC) and multiconfigurational methods in form of cumulant-approximated second-order perturbation theory, based on the density matrix renormalization group (DMRG). We find that it is more favorable for H2 to bind to Ni than to Fe, in agreement with previous CC and DMRG calculations. The accuracy of CAS-srDFT is comparable to both CC and DMRG, despite that much smaller active spaces were employed. This enhanced efficiency at smaller active spaces shows that CAS-srDFT can become a useful method for bio-inorganic chemistry.