Correlating the Crystal Structure and Optical Response of DNA-Stabilized Ag16Cl2 Clusters.

We investigate the electronic structure and optical response of the DNA-stabilized silver cluster (DNA)2-Ag16Cl2 using density functional theory in its ground-state and linear-response forms. Our calculations are based on experimental crystal data, where DNA strands, mutated by guanosine-inosine change, are protecting an inorganic Ag16Cl2 core [CerretaniNanoscale Adv.2022, 4, 3212-3217]. We find a remarkable sensitivity of the computed optical absorption spectrum on (i) the level of approximations of how the clusters' environment is modeled (implicit continuum solvent model, with or without the explicit crystal water molecules in the vicinity of the DNA strands), (ii) the level of the approximations regarding the electron-electron exchange-correlation functionals, and (iii) the minute differences in crystal packing in subclusters in the crystal unit cell. Our work highlights the challenges for high-fidelity computational modeling of the electronic structure of these hybrid bionano materials and points to need to further develop computational methods toward efficient sampling of dynamical behavior to understand better the correlations between measured and computed properties.