  We investigate retrieval of the stellar rotation signal for Proxima Centauri.
We make use of high-resolution spectra taken with uves and harps of Proxima
Centauri over a 13-year period as well as photometric observations of Proxima
Centauri from asas and hst. We measure the H{\alpha} equivalent width and
H{\alpha} index, skewness and kurtosis and introduce a method that investigates
the symmetry of the line, the Peak Ratio, which appears to return better
results than the other measurements. Our investigations return a most
significant period of 82.6 $\pm$ 0.1 days, confirming earlier photometric
results and ruling out a more recent result of 116.6 days which we conclude to
be an alias induced by the specific harps observation times. We conclude that
whilst spectroscopic H{\alpha} measurements can be used for period recovery, in
the case of Proxima Centauri the available photometric measurements are more
reliable. We make 2D models of Proxima Centauri to generate simulated
H{\alpha}, finding that reasonable distributions of plage and chromospheric
features are able to reproduce the equivalent width variations in observed data
and recover the rotation period, including after the addition of simulated
noise and flares. However the 2D models used fail to generate the observed
variety of line shapes measured by the peak ratio. We conclude that only 3D
models which incorporate vertical motions in the chromosphere can achieve this.
