Effect of Pressure on the Distribution of Electrons in a Cluster of H(2)S

[Image: see text] We carry out a theoretical study of the effect of pressure on the atomic and electronic distribution of a cluster made of 155 H(2)S molecules. The pressure was modeled by bringing the cluster into a spherical container made of 500 helium atoms and reducing the diameter of the container. We did ab initio molecular calculations using DFT. At the lowest pressure, the S–H–S angle between two neighboring H(2)S molecules has a distribution with a mean value of 167.1°. This angle will be shorter as pressure increases, reaching a distribution with a mean value of 125.5° at the highest pressure. Changes in this angle result from a strong S–S interaction, displacing the H atoms from the line joining the sulfur atoms. This rearrangement of the atomic distribution generates hydrogen-rich spatial regions. We analyzed the evolution of Mulliken charges on S and H atoms in the cluster with pressure, finding that electrons move from S to H atoms, suggesting that these hydrogen-rich regions should be responsible for the electrical conductivity and, consequently, also for the superconductivity in solid H(2)S under pressure.