faq:cutoff
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| faq:cutoff [2014/02/20 13:57] – Initial version of this page created krack | faq:cutoff [2020/08/21 10:15] (current) – external edit 127.0.0.1 | ||
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| ===== How can one guess a reasonable cutoff value? ===== | ===== How can one guess a reasonable cutoff value? ===== | ||
| - | **This is for the impatient CP2K user:** As a rule of thumb one can multiply the largest exponent of the Gaussian basis sets employed by 40 to obtain a reasonable guess for the cutoff value suited for your systems | + | **This is for the impatient CP2K user:** As a rule of thumb one can multiply the largest exponent of the Gaussian basis sets employed by **40** to obtain a reasonable guess for the cutoff value in Rydberg. The first column of the CP2K basis set format contains the Gaussian exponents, e.g. for the oxygen DZVP-MOLOPT-SR-GTH basis set you may find a value of about 10.4 and the corresponding hydrogen DZVP-MOLOPT-SR-GTH basis set employs a largest exponent of about 10.0. Thus a cutoff value of **10*40 = 400 Rydberg** would be a reasonable guess for a cutoff value to start with. The following values |
| < | < | ||
| Total charge density on r-space grids: | Total charge density on r-space grids: | ||
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