Date of Original Version
We show that for conformally invariant two-dimensional systems, the amplitude of the finite-size corrections to the free energy of an infinitely long strip of width L at criticality is linearly related to the conformal anomaly number c, for various boundary conditions. The result is confirmed by renormalization-group arguments and numerical calculations. It is also related to the magnitude of the Casimir effect in an interacting one-dimensional field theory, and to the low-temperature specific heat in quantum chains.
Blöte, H. W. J., Cardy, J. L., & Nightingale, M. P. (1986). Conformal invariance, the central charge, and universal finite-size amplitudes at criticality. Physical Review Letters, 56(7), 742-745. doi: 10.1103/PhysRevLett.56.742
Available at: http://dx.doi.org/10.1103/PhysRevLett.56.742