Metallic lithium becomes semiconducting when it is under pressure. That has been predicted theoretically and recently confirmed experimentally. Another example which shows metal to insulator transition at high pressure is sodium. Besides these interesting materials, many simple hydrides shows insulator to metal transition at high pressure where the superconductivity with high Tc is expected. I will study such materials that show metal-insulator transitions at high pressure by by using first-principles calculations.
This time I will give an basic theory of the first-principles calculations based on the LDA, as well as the theory called GW-approximation which is used in more accurate evaluation of the band gaps than the usual LDA. I will also instroduce my future works.
リチウムは高圧条件下におくと金属的性質から絶縁体の性質になることが理論的にも実験的にも示されている。ナトリウムにも同様のことがいえる。また、高圧下で超伝導Tcが高く予測されているものでも同様な性質がおこるものが多い。
高圧下でこのような転移を示す物質を第一原理計算で研究する予定である。今回の発表ではLDAやそれらよりも正確にバンドギャップを示すGW近似にもとづく第一原理計算の概観も紹介する。 併せて今後行なう研究も紹介する。