“intra_rms” calculates rms fit values for all states of an object over an atom selection relative to the indicated state. Coordinates are left unchanged. The rms values are returned as a python array.
from pymol import cmd
rms = cmd.intra_rms("(name ca)",1)
print rms
fit | rms | rms_cur | intra_fit | intra_rms_cur | pair_fit | cmd.intra_rms | commands