Electronic structures of YCo4B and YCo3B2 are calculated in a self-con
sistent linear muffin-tin orbital method and the atomic sphere approxi
mation. The effects of B atom in these compounds are discussed, by com
paring the calculated local density-of-states curves with those of YCo
5 obtained previously. A good agreement between the calculated and obs
erved values of the low-temperature specific heat coefficient for YCo3
B2 is obtained. Spin-polarized band calculations are also carried out
and the local spin and orbital magnetic moments are evaluated at each
Co atom site in YCo4B. It is found that the Co moment on 6i site is sm
all, while the Co moment on 2c site is large. On the other hand, YCo3B
2 is found to be non-magnetic. These results are consistent with the o
bserved ones and can be explained by the mixing model between 3d-state
s of Co and 2p-states of B. (C) 1998 Elsevier Science B.V. All rights
reserved.