  We investigate the electromagnon in magnetoferroelectrics RMn$_2$O$_5$ using
combined molecular-spin dynamics simulations. We identify the origin of the
electromagnon modes observed in the optical spectra and reproduce the most
salient features of the electromagnon in these compounds. We find that the
electromagnon frequencies are very sensitive to the magnetic wave vector along
the $a$ direction. We further investigate the electromagnon in magnetic field.
Although the modes frequencies change significant under magnetic field, the
static dielectric constant electromagnon does not change much in the magnetic
field.
