First-principles study of the lattice thermal conductivity of the Si–O–H system at high pressure

SiOH 2 , SiO 2 H 2 , and (SiO 2 ) 2 (H 2 O) exhibit ultrahigh thermal conductivities under high pressure. The incorporation of H 2 O into Si to form SiOH 2 leads to reduced thermal conductivity, possibly explaining Uranus and Neptune's low internal heat flux.