大规模DFT程序CONQUEST中多站定域轨道的高效计算
Efficient Calculations with Multisite Local Orbitals in the large-scale DFT Code CONQUEST
摘要：
在大规模密度泛函理论计算程序CONQUEST中引入了多位定域轨道，它是由靶原子及其邻近原子的赝原子轨道的线性组合形成的。多位点局部轨道对应于局部分子轨道，使得所需的局部轨道的数目可以是最小的。通过使用局部滤波器对角化（LFD）方法[Phys. Rev. B 2009，80，205 - 104]确定多位点支持函数。在LFD方法中引入了两种新的方法，即双截断法和平滑法，以提高LFD方法的效率和稳定性。在CONQUEST中通过有效的稀疏矩阵乘法构造了具有多位点局部轨道的哈密顿矩阵和重叠矩阵。对体硅、铝和DNA体系的能量、几何性质和能带结构的计算结果表明，本文方法具有较高的计算效率和计算精度。同时也证实了本方法对占据和未占据能带结构的可表示性。
英文摘要：
Multisite local orbitals, which are formed from linear combinations of pseudo-atomic orbitals from a target atom and its neighbor atoms, have been introduced in the large-scale density functional theory calculation code CONQUEST. Multisite local orbitals correspond to local molecular orbitals so that the number of required local orbitals can be minimal. The multisite support functions are determined by using the localized filter diagonalization (LFD) method [Phys. Rev. B 2009, 80, 205104]. Two new methods, the double cutoff method and the smoothing method, are introduced to the LFD method to improve efficiency and stability. The Hamiltonian and overlap matrices with multisite local orbitals are constructed by efficient sparse-matrix multiplications in CONQUEST. The investigation of the calculated energetic and geometrical properties and band structures of bulk Si, Al and DNA systems demonstrate the accuracy and the computational efficiency of the present method. The representability of both occupied and unoccupied band structures with the present method has been also confirmed.
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