Photoelectron properties of DNA and RNA bases from many-body perturbation theory

The photoelectron properties of DNA and RNA bases are studied using many-body perturbation theory within the $GW$ approximation, together with a recently developed Lanczos-chain approach. Calculated vertical ionization potentials, electron affinities, and total density of states are in good agreement with experimental values and photoemission spectra. The convergence benchmark demonstrates the importance of using an optimal polarizability basis in the $GW$ calculations. A detailed analysis of the role of exchange and correlation in both many-body and density-functional theory calculations shows that while self-energy corrections are strongly orbital-dependent, they nevertheless remain almost constant for states that share the same bonding character. Finally, we report on the inverse lifetimes of DNA and RNA bases that are found to depend linearly on quasiparticle energies for all deep valence states. In general, our $G_0{W}_0$-Lanczos approach provides an efficient yet accurate and fully converged description of quasiparticle properties of five DNA and RNA bases.

Figure 1

Ground-state structures of five DNA and RNA bases including G9K-guanine, adenine, C1-cytosine, thymine, and uracil.

Figure 2

Eigenvalue distribution of the optimal polarizability basis for cytosine. The inset plot shows the eigenvalues in a log scale.

Figure 3

Real-space representation of optimal-polarizability basis elements for cytosine, labeled with their eigenvalue indexes. Due to the delocalized nature of the optimal basis in the third row, the images in the third row were generated with a smaller isovalue and shown at a larger scale than those in the first two rows.

Figure 4

Convergence benchmark of VIP and VEA of five DNA and RNA bases with respect to the number of optimal-polarizability basis elements $N_P$, and augmented plane-wave cutoff $E^{*}$. Results using $E^{*}=$ 95.2 and 136.1 eV are plotted in dashed-blue lines and solid-red lines, respectively.

Figure 5

VIP and VB-VEA of five DNA and RNA bases from our DFT and $G_0{W}_0$ calculations. Here we adopt the mean values of various experimental data listed in Table . The experimental ranges are $8.0\sim 8.3$, $8.3\sim 8.5$, $8.8\sim 8.9$, $9.0\sim 9.2$, and $9.4\sim 9.6$ eV for G, A, C, T, and U, respectively.

Figure 6

Convergence behavior of vertical ionization potentials of several $n$ states in DNA and RNA bases with respect to the number of optimal polarizability basis, $N_P$, and augmented plane-wave cutoff, $E^{*}$. These states are cytosine’s HOMO-1 state, thymine’s HOMO-1 state, and uracil’s HOMO-1 and HOMO-3 states. Results using $E^{*}=$ 95.2 and 136.1 eV are plotted in dashed-blue lines and solid-red lines, respectively.

Figure 7

Valence-bound and dipole-bound VEAs and their corresponding QP states, calculated at the DFT-PBE level, in the five DNA and RNA bases. Values listed below are VEAs in the unit of eV.

Figure 8

(a) Experimental valence photoemission spectrum (shaded gray area), DFT-PBE DOS (blue dashed lines), and $G_0{W}_0$ DOS (red solid lines). Both DOS curves are shifted to match the first VIP of experimental data. Experimental PES spectra of G, A, C, T, and U are extracted from Refs. 37,8,8,8, and38, respectively. The theoretical DOS have been obtained through a Lorentzian broadening defined by a width of $0.4$ eV. (b) $G_0{W}_0$ QP energies and inverse lifetime for valence states (unit: eV).

Figure 9

The role of exchange and correlation in the $G_0{W}_0$ self-energy corrections to Kohn-Sham eigenvalues of 25 valence states and 10 conduction states in adenine. (a) $G_0{W}_0$ exchange energy ${\Sigma }_n^{\mathrm{X}}$, (b) $G_0{W}_0$ correlation energy ${\Sigma }_n^{\mathrm{C}}$, (c) the sum of $G_0{W}_0$ exchange and correlation energy ${\Sigma }_n^{\mathrm{XC}}$ (filled symbols) and DFT XC energy ${\varepsilon }_n^{\mathrm{XC}}$ (unfilled symbols), and (d) the difference between $G_0{W}_0$ and DFT exchange-correlation energy, ${\Delta }_n^{\mathrm{XC}}\equiv {\Sigma }_n^{\mathrm{XC}}-{\varepsilon }_n^{\mathrm{XC}}$. Four types of molecular orbitals are illustrated in (a)–(d), corresponding to ${\sigma }_{ss}$, ${\sigma }_{sp}$, $n$, and $\pi$ characters.