Evaluation of exchange‐correlation functionals for time‐dependent density functional theory calculations on metal complexes

Abstract

The electronic absorption spectra of a range of copper and zinc complexes have been simulated by using time-dependent density functional theory (TD-DFT) calculations implemented in Gaussian03. In total, 41 exchange-correlation (XC) functionals including first-, second-, and third-generation (meta-generalized gradient approximation) DFT methods were compared in their ability to predict the experimental electronic absorption spectra. Both pure and hybrid DFT methods were tested and differences between restricted and unrestricted calculations were also investigated by comparison of analogous neutral zinc(II) and copper(II) complexes. TD-DFT calculated spectra were optimized with respect to the experimental electronic absorption spectra by use of a Matlab script. Direct comparison of the performance of each XC functional was achieved both qualitatively and quantitatively by comparison of optimized half-band widths, root-mean-squared errors (RMSE), energy scaling factors (epsilon(SF)), and overall quality-of-fit (Q(F)) parameters. Hybrid DFT methods were found to outperform all pure DFT functionals with B1LYP, B97-2, B97-1, X3LYP, and B98 functionals providing the highest quantitative and qualitative accuracy in both restricted and unrestricted systems. Of the functionals tested, B1LYP gave the most accurate results with both average RMSE and overall Q(F) < 3.5% and epsilon(SF) values close to unity (>0.990) for the copper complexes. The XC functional performance in spin-restricted TD-DFT calculations on the zinc complexes was found to be slightly worse. PBE1PBE, mPW1PW91 and B1LYP gave the most accurate results with typical RMSE and Q(F) values between 5.3 and 7.3%, and epsilon(SF) around 0.930. These studies illustrate the power of modern TD-DFT calculations for exploring excited state transitions of metal complexes.

TD-DFT Benchmark on Inorganic Pt(II) and Ir(III) Complexes

“…More specifically they pointed out that careful choice of the functional with a correct amount of HF exchange can provide accurate predictions of electronic absorption spectra when one deals with metal complexes. 76 Our investigation fully confirms that the use of 20-30 % of HF exchange provides, in most cases, accurate results. Moreover, as one can see in Table 1, it is difficult to assign unambiguously specific computed excitations to their experimental counterparts for such type of compounds.…”

Photoluminescent columnar zinc(II) bimetallomesogen of tridentate [ONO]-donor Schiff base ligand

“…Time-dependent DFT (TD-DFT) calculations are carried out to study the electronic transitions observed in the experimental ultraviolet-visible spectroscopy (UV−Vis) spectra. [31] DFT has become a very important tool as it allows considerable insight into the electronic structures of transition metal complexes. The GAUSSIAN 09 program package [32] was employed to carry out DFT calculations at the Becke's three-parameter functional and Lee-Yang-Parr functional (B3LYP) levels [33,34] of calculation.…”

Directions for Use of Density Functional Theory: A Short Instruction Manual for Chemists

“…In both cases HGGA functionals did not offer an improvement. In almost all the cases the calculations underestimated the experimental excitation energies (Holland & Green, 2010) Nevertheless, it is maybe worth noting that the OPBE and the OBLYP functionals, which were shown to perform well in other cases, were not considered.…”