# CFOUR_GENBAS_1

> This keyword applies only to Hydrogen and Helium atoms and specifies the number of contracted Gaussian functions per shell. There is usually no need to use this keyword, but it can be useful for using a subset of the functions in a particular entry in the `GENBAS` file, particularly for generally contracted WMR basis sets. For example, if entry H:BASIS in the `GENBAS` file contains 7 contracted s functions, 4 p functions and a single d function, then setting GENBAS_1=730 would eliminate the last p function and the d function. Default: use the unaltered `GENBAS` entry.

> - Type: string
> - Default: No Default