howto:lrigpw
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| howto:lrigpw [2017/05/08 08:31] – [How to use it] dgolze | howto:lrigpw [2017/05/14 13:31] – [Introduction] dgolze | ||
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| ===== Introduction ===== | ===== Introduction ===== | ||
| - | Density functional theory (DFT) calculations in CP2K employ the Gaussian and plane waves (GPW) method. In GPW, the description of the total density on realspace grids is typically the computationally most expensive part. By introducing a local resolution-of-the-identity (LRI) approach, the linear scaling of the GPW approach can be retained, while reducing the prefactor for the grid operations. The combined approach, LRIGPW, is comprehensively described in [[doi> | + | Density functional theory (DFT) calculations in CP2K employ the Gaussian and plane waves (GPW) method. In GPW, the description of the total density on realspace grids is typically the computationally most expensive part. By introducing a local resolution-of-the-identity (LRI) approach, the linear scaling of the GPW approach can be retained, while reducing the prefactor for the grid operations. The combined approach, LRIGPW, is comprehensively described in [[doi> |
| In LRIGPW, the atomic pair densities $\rho_{\mathrm{AB}}$ are approximated by an expansion in a set of fit functions centered at atom A $\{f_i^{\mathrm{A}}(\mathbf{r})\}$ and atom B $\{f_j^{\mathrm{B}}(\mathbf{r})\}$, | In LRIGPW, the atomic pair densities $\rho_{\mathrm{AB}}$ are approximated by an expansion in a set of fit functions centered at atom A $\{f_i^{\mathrm{A}}(\mathbf{r})\}$ and atom B $\{f_j^{\mathrm{B}}(\mathbf{r})\}$, | ||
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| * many SCF steps | * many SCF steps | ||
| Using LRI, the SCF step is accelerated and therefore single point calculations profit most. For molecular dynamics, where the wave function can be extrapolated from the previous step, the SCF converges quickly. Also in this case speed-ups can be obtained depending on the grid cutoff and system. | Using LRI, the SCF step is accelerated and therefore single point calculations profit most. For molecular dynamics, where the wave function can be extrapolated from the previous step, the SCF converges quickly. Also in this case speed-ups can be obtained depending on the grid cutoff and system. | ||
| - | Note that LRIGPW comes with higher memory requirements than the standard GPW scheme. However, this is typically not a problem on HPC platforms. | + | Note that LRIGPW comes with higher memory requirements than the standard GPW scheme. However, this is typically not a problem on HPC platforms, but might limit the usage on smaller clusters. |
| ===== Example input files ===== | ===== Example input files ===== | ||
| * Ice XV: {{: | * Ice XV: {{: | ||
howto/lrigpw.txt · Last modified: 2024/01/03 13:17 by oschuett