The long-term V/R variation is one of the most puzzling phenomena
concerning Be stars.
The periods of the variations range from years to decades;
the average period is about 
yr
(Copeland, Heard 1963; Hirata, Hubert-Delplace 1981).
This period range is much longer than
the rotation periods of the central stars and cool envelopes.
In addition, the variations are always accompanied
by profile shifts:
the profile as a whole shifts blueward (redward) when the red (violet)
component is stronger
(McLaughlin 1961, 1962, 1963, 1966; Hubert et al. 1987).
A schematic picture of the profile variation is given by Huang (1975).
Because of their bizarreness, the long-term V/R variations have been extensively studied. Unfortunately, no widely-accepted models exist yet. However, it is now accepted that this phenomenon can be attributed to variations in cool envelopes surrounding the stars (e.g., Poeckert 1982; Hirata, Kogure 1984; Ballereau, Chauville 1989). Thus, any satisfactory model for the long-term V/R variations enables us to probe the disk structures and distributions of physical quantities in equatorial disks.
In Okazaki (1991, hereafter Paper I) we proposed a dynamical model based on a theory of global oscillations in nonself-gravitating, geometrically thin (i.e., nearly Keplerian) disks. According to this theory of global oscillations, the possible global oscillations in nearly Keplerian disks are very low-frequency, one-armed (i.e., m=1) oscillations alone (Kato 1983, 1989; Okazaki, Kato 1985; Adams et al. 1989; Okazaki 1991). Hence, this model suggests that the long-term V/R variations are phenomena caused by the global m=1 oscillations in the equatorial disks of Be stars. Studying the m=1 eigenmodes of linear isothermal oscillations in the isothermal equatorial disks, we found in Paper I that the one-armed oscillation model naturally explains the observed periodicities of the long-term V/R variations.
Recently, based on 3D radiative-transfer calculations,
Hummel and Hanuschik (1994) and Hanuschik et al. (1995)
presented some examples of
the H
emission line profiles from disks
with the perturbation patterns found in Paper I.
They found that the computed profiles are in agreement with
the observed line-profile variability.
The purpose of this paper is to discuss our examination of the behavior of the line-profile variations due to the m=1 perturbation patterns for various values of the disk parameters. Since we were concerned with the global features of V/R variations, we adopted a simplified treatment, which is described in later sections. We computed the line profiles by integrating the fluxes along the line-of-sights through the entire disk region. Similar methods have often been used to calculate the profiles of optically-thick lines emitted from disks (e.g., Marlborough 1969, 1970; Poeckert, Marlborough 1978 for Be-star envelopes, and Horne, Marsh 1986; Adam et al. 1989a,b for accretion disks).
In this paper we show that,
in general terms, the line-profile variabilities
caused by the m=1 perturbation patterns are in agreement with
the observed V/R variations.
We also show that the amplitude of the profile shift associated with
the V/R variation
is sensitive to the adopted detailed disk structure.
In the model described,
disks with a local density which decreases as steeply as 
exhibit remarkable V/R variations
for a wide range of disk parameters.