  Classical configurations in the CP^{N-1} model on R^1 x S^1 is studied with
twisted boundary conditions. Starting from fractional instantons with the Z_N
twisted boundary conditions, we review briefly the relevance of our study to
resurgence phenomenon in field theory. We consider primarily configurations
composed of multiple fractional instantons, called "neutral bions", which are
identified as "perturbative infrared renormalons". We construct an explicit
ansatz corresponding to topologically trivial configurations containing one
fractional instanton (nu=1/N) and one fractional anti-instanton (nu=-1/N),
which is guaranteed to become a solution of field equations asymptotically for
large separations. The attractive interactions between the instanton
constituents from small to large separations are found to be consistent with
the standard separated-instanton calculus. Our results suggest that the ansatz
enables us to study bions and the related physics for a wide range of
separations. This talk is mainly based on our recent work published in JHEP
1406, 164 (2014) [arXiv:1404.7225 [hep-th]].
