howto:cdft
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| howto:cdft [2020/08/21 10:15] – external edit 127.0.0.1 | howto:cdft [2022/05/18 20:24] – Update for new CDFT forces based on Hirshfeld partitioning of the electron density (CP2K version 10 #2111) cahart | ||
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| <note important> | <note important> | ||
| - | CP2K version 5.1 or higher is needed to perform CDFT simulations. | + | CP2K version 5.1 or higher is needed to perform CDFT simulations. CP2K version 10 or higher is needed to perform CDFT force calculations with Hirshfeld based constraints. |
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| * spin specific constraint ($\rho^{\uparrow/ | * spin specific constraint ($\rho^{\uparrow/ | ||
| - | The Becke and Hirshfeld space partitioning schemes can be used as constraint weight functions in CP2K. The main differences between these two constraints will be explained in a subsequent section. Please note that Becke constraints have been tested much more extensively. | + | The Becke and Hirshfeld space partitioning schemes can be used as constraint weight functions in CP2K. The main differences between these two constraints will be explained in a subsequent section. |
| - | When CDFT is used in a molecular dynamics or a geometry optimization simulation, additional force terms arising from the constraints are calculated | + | When CDFT is used in a molecular dynamics or a geometry optimization simulation, additional force terms arising from the constraints are calculated |
| \begin{equation} | \begin{equation} | ||
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| ==== Available constraints ===== | ==== Available constraints ===== | ||
| - | The CDFT module in CP2K currently supports using Becke or Hirshfeld | + | The CDFT module in CP2K currently supports using Becke or Hirshfeld based constraints. The main aspects of these weight functions and their use as CDFT constraints will be explained in this section. Weight function specific settings are defined in the sections [[inp> |
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| == Hirshfeld constraints == | == Hirshfeld constraints == | ||
| - | Hirshfeld constraints are cheaper to construct than Becke constraints in large systems because Hirshfeld constraints are essentially just weighted sums of spherical Gaussian functions. The keywords [[inp> | + | Hirshfeld constraints are cheaper to construct than Becke constraints in large systems because Hirshfeld constraints are essentially just weighted sums of spherical Gaussian functions. The keywords [[inp> |
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| + | The shape function keyword accepts two values: Gaussian or Density. | ||
| * The first choice implies that the CDFT weight function for each atom is a single Gaussian function whose radius is controlled by the GAUSSIAN_SHAPE keyword. By default, tabulated covalent radii are used as the radii of the Gaussian, but it is also possible to select van der Waals radii or to define custom radii. | * The first choice implies that the CDFT weight function for each atom is a single Gaussian function whose radius is controlled by the GAUSSIAN_SHAPE keyword. By default, tabulated covalent radii are used as the radii of the Gaussian, but it is also possible to select van der Waals radii or to define custom radii. | ||
| - | * The latter choice implies that the atomic weight function are constructed from isolated atomic densities which are expanded in terms of multiple spherical Gaussians. This choice | + | * The latter choice implies that the atomic weight function are constructed from isolated atomic densities which are expanded in terms of multiple spherical Gaussians. This choice |
| ==== Selected examples | ==== Selected examples | ||
howto/cdft.txt · Last modified: 2024/01/03 13:20 by oschuett