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相关概念视频

Fermi Level Dynamics01:12

Fermi Level Dynamics

285
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
285
Fast Fourier Transform01:10

Fast Fourier Transform

389
The Fast Fourier Transform (FFT) is a computational algorithm designed to compute the Discrete Fourier Transform (DFT) efficiently. By breaking down the calculations into smaller, manageable sections, the FFT significantly reduces the computational complexity involved. Direct computation of an N-point DFT requires N2 complex multiplications, whereas the FFT algorithm needs only (N/2)log⁡2N multiplications, offering a much faster performance.
The computational efficiency of the FFT becomes...
389
Discrete-Time Fourier Series01:20

Discrete-Time Fourier Series

304
The Discrete-Time Fourier Series (DTFS) is a fundamental concept in signal processing, serving as the discrete-time counterpart to the continuous-time Fourier series. It allows for the representation and analysis of discrete-time periodic signals in terms of their frequency components. Unlike its continuous counterpart, which utilizes integrals, the calculation of DTFS expansion coefficients involves summations due to the discrete nature of the signal.
For a discrete-time periodic signal x[n]...
304
Discrete Fourier Transform01:15

Discrete Fourier Transform

325
The Discrete Fourier Transform (DFT) is a fundamental tool in signal processing, extending the discrete-time Fourier transform by evaluating discrete signals at uniformly spaced frequency intervals. This transformation converts a finite sequence of time-domain samples into frequency components, each representing complex sinusoids ordered by frequency. The DFT translates these sequences into the frequency domain, effectively indicating the magnitude and phase of each frequency component present...
325
Mechanistic Models: Compartment Models in Algorithms for Numerical Problem Solving01:29

Mechanistic Models: Compartment Models in Algorithms for Numerical Problem Solving

81
Mechanistic models play a crucial role in algorithms for numerical problem-solving, particularly in nonlinear mixed effects modeling (NMEM). These models aim to minimize specific objective functions by evaluating various parameter estimates, leading to the development of systematic algorithms. In some cases, linearization techniques approximate the model using linear equations.
In individual population analyses, different algorithms are employed, such as Cauchy's method, which uses a...
81
Relation of DFT to z-Transform01:20

Relation of DFT to z-Transform

425
The Discrete Fourier Transform (DFT) is a crucial tool for analyzing the frequency content of discrete-time signals. It converts a sequence of N samples from the time domain into its corresponding sequence in the frequency domain, where each sample represents a specific frequency component.
To understand how the DFT works, it's helpful to consider the z-transform, which is a method for representing discrete sequences in the complex frequency domain. The z-transform involves summing the...
425

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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
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在HPC架构上的大规模DFT固有值问题上的子空间递归费米运算符扩展策略.

Sameer Khadatkar1, Phani Motamarri1

  • 1Department of Computational and Data Sciences, Indian Institute of Science, Bengaluru 560012, India.

The Journal of chemical physics
|July 20, 2023
PubMed
概括

本研究介绍了多项式扩展方法,以加速材料建模中的量子力学计算. 这些新方法为大规模密度函数理论模拟提供了传统对角化的更有效的替代方案.

科学领域:

  • 计算材料科学科学 计算材料科学
  • 量子力学就是量子力学.
  • 密度函数理论密度函数理论

背景情况:

  • 科恩-沙姆密度函数理论 (DFT) 的计算对于材料建模至关重要,但在计算上是密集的.
  • 传统方法涉及解决具有立方缩放复杂性的非线性自值问题.
  • 代投影方法是高效的,但面临的瓶雷利-里茨投影和子空间对角化对大型系统.

研究的目的:

  • 探索多项式扩展方法,特别是递归的费米运算子扩展,作为子空间对角化的替代方案.
  • 为了降低与大规模的DFT计算相关的计算成本.
  • 将这些新方法的性能与传统的对角化技术进行比较.

主要方法:

  • 实施和测试各种递归多项式扩展算法.
  • 与显式对角化方法的详细比较.
  • 在中央处理器 (CPU) 和图形处理器 (GPU) 架构上的性能评估.
  • 评估准确性,计算效率,扩展和能源效率.

主要成果:

  • 多项式扩展方法显示了在DFT中降低计算成本的潜力.
  • 对比分析揭示了不同扩展方法和传统对角化之间的性能权衡.

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  • 性能指标包括精度,速度,可扩展性和各种硬件上的能耗.
  • 结论:

    • 递归多项式扩展为加速大规模DFT模拟提供了一个有希望的途径.
    • 选择的方法取决于特定的系统大小和硬件架构.
    • 这项工作有助于更高效和可扩展的材料科学量子力学计算.