This block defines for which frequencies the polarizabilities
will be calculated. If it is not present, the static ($\omega = 0$) response
is calculated.
Each row of the block indicates a sequence of frequency values, the
first column is an integer that indicates the number of steps, the
second number is the initial frequency, and the third number the final
frequency. If the first number is one, then only the initial value is
considered. The block can have any number of rows. Consider the next example: