approximately with experimental values because M may have linear or a complex structure. Further, it may also be mentioned that it is not the length of M-$^4$He bond which changes much with atoms added to the cluster but the projection of this bond on the plane $\perp$ to the axis of the rotor which should be considered to explain the changes in $I_N$ with added $^4$He atoms that we observe through experiments.

The experimental observations seem to indicate that the part of M:$^4$He$_N$ cluster which rotates, to a good approximation as a rigid rotor, has fewer than $N^*$ $^4$He atoms in clusters of $N >> N^*$. This agrees with our suggestion that $n_c$ (= 1 or 2, or so) atoms move from orbit 1 to orbit 2 with increasing $N$ beyond $N^*$. However, the physics of this possibility is not yet very clear.

In the light of the fact that $^4$He atoms in superfluid state make a close packed arrangement of their wave packets (CPA-WP) supported by a number of experimental observations such as the observation of Stark effect of roton transition seen through microwave absorption [@jains] and the unequivocal conclusions of a number of theoretical studies [@jain2; @jain1; @simanta], 