• electrical conductivity;
  • electron hole;
  • hydrogen;
  • olivine;
  • upper mantle

[1] The influence of hydrogen on the electronic states in olivine was investigated by the first-principle calculations combined with the models of the mobility of electrons. We find that the dissolution of hydrogen modifies the electronic states when hydrogen is dissolved as charged defects but there is little modifications to the electronic structure when hydrogen is dissolved as a neutral defect such as two protons at M-site. In the former case an impurity state is created just above the valence band providing a mechanism of impurity conduction. The electrical conductivity calculated from this model using a model of the mobility appropriate for “polaron” mechanism of conduction shows a good agreement with the experimental observations on hydrated olivine. We conclude that the enhanced electrical conductivity in olivine by the dissolution of hydrogen may partly due to the enhancement of electronic conduction. Possible implications for high-temperature creep are also discussed.