Linear chains of hydrogen molecules under pressure: An extreme-pressure continuum model study.

New analytical gradients of the electronic energy of a confined molecular system within the extreme-pressure continuum model are presented and applied to the study of the equilibrium geometries of linear chains of hydrogen molecules nH₂ under pressures. The decrease in inter- and intramolecular H–H distances with the increase in the pressure has been studied up to 80 GPa. We have also shown that the compression of the bond-lengths can be interpreted in terms of the effect of the confining potential of the electron density of the molecular systems. [ABSTRACT FROM AUTHOR]