Sakuma R, Miyake T, Aryasetiawan F
Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan. Japan Science and Technology Agency, CREST, Japan.
J Phys Condens Matter. 2009 Feb 11;21(6):064226. doi: 10.1088/0953-8984/21/6/064226. Epub 2009 Jan 20.
Vanadium dioxide is insulating below 340 K in experiments, whereas the band structure calculated in the local density approximation (LDA) is gapless. We study the self-energy effects using the ab initio GW method. We found that the self-energy depends strongly on the energy, and proper treatment of the dynamical effect is essential for getting precise quasiparticle energies. Off-diagonal matrix elements in the Kohn-Sham basis are also important for disentangling bands. Inclusion of the two effects opens up a direct gap. Our results also suggest that one-shot GW on top of LDA is not enough, and the impact of self-consistency is significant.
在实验中，二氧化钒在340K以下是绝缘的，而用局域密度近似（LDA）计算的能带结构是无带隙的。我们使用从头算GW方法研究自能效应。我们发现自能强烈依赖于能量，并且对动力学效应进行适当处理对于获得精确的准粒子能量至关重要。在Kohn-Sham基中的非对角矩阵元对于解开能带也很重要。包含这两种效应会打开一个直接带隙。我们的结果还表明，在LDA之上进行单次GW计算是不够的，自洽性的影响很大。
