TDDFT calculations for excitation spectra of solids and superstructures utilizing mGGA

Time-dependent Density Functional Theory (TDDFT);semiconductor;semiconductor alloys;optical spectrum;Linearized Augmented Slater-type Orbital (LASTO);meta-generalized gradient approximation (mGGA);Local Density Approximation (LDA);cluster averaging method;Kohn-Sham;exchange-correlation potential;transition matrix element

Ning, Zhenhua

关键词: Time-dependent Density Functional Theory (TDDFT);    semiconductor;    semiconductor alloys;    optical spectrum;    Linearized Augmented Slater-type Orbital (LASTO);    meta-generalized gradient approximation (mGGA);    Local Density Approximation (LDA);    cluster averaging method;    Kohn-Sham;    exchange-correlation potential;    transition matrix element;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/78357/NING-DISSERTATION-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The first principles study plays a very important role in developing new generation of materials, suchas organic semiconductors and long polymer chains, as well as understanding of physical properties ofnanoparticles , inorganic semiconductors and semiconductor alloys. In this work, we start from the Kohn-Sham one-particle equation Schr¨odinger equation and solve it by expanding its eigenfunctions in terms of the linear augmented-slater-type orbits(LASTO) under full potential with the exchange-correlation potentialfunctional given by meta-generalized gradient approximation(mGGA). Our theoretical results were comparedto WIEN2K’s, and good agreement was obtained. As the application, we apply TDDFT plus mGGA tocalculate optical spectra for bulk solids. The result shows good agreement with experimental data.III-V ternary alloys AxB1−xC are promising materials for optoelectronic, high-speed electronic andmicrowave applications, such as infrared emitting diodes and detectors, high electron mobility transistors,heterojunction bipolar transistors, quantum-dot lasers, modulators and ultrafast switches. We adoptedthe TDDFT theory and the cluster averaging method to compute the spectra of III-V ternary alloys witharbitrary concentration x. We find great agreement between theoretical and experimental data. The successof this method is mainly because that we approximate the transition matrix elements by the LDA p-matrixelements via (mGGA) which contains the singularity of the type fXC,00(q) ∼ 1/q2 as q → 0. Thus, Ourstudies provide some insight into the theoretical calculation of optical spectra of semiconductor alloys.