(Pramana – J. Phys. 80(2), 237–249 (2013))

We followed [33] for notation and definitions on p. 239, but erred in (i) not stating explicitly that we do so and (ii) in copying verbatim (arXiv:0712.4270) equations (1) and (2) as well as some sentences near them. We regret this error. Our results (in Sec. 5) are however completely new and have been obtained only by us.