A clear distinction between stages 1 and 2 in As is provided by the sign change in the pressure coefficient of d1 and ρd1 around 16 GPa (Fig. ) due to the anomalous increase (decrease) of d1 (ρd1) that occurs in stage 2 above that pressure. These calculated anomalous trends agree with the results of previous calculations of the effect of pressure on As-I , and on As trimers , which left unnoticed. Unfortunately, the calculated increase of d1 has still not been experimentally confirmed in pure As due to the limited resolution of the only published results based on a lab-based diffractometer and the lack of more accurate results comming from synchrotron-based X-ray diffraction measurements. In any case, it must be pointed out that our results for As are also consistent with the increase of the short intrachain d1 distance in Se at low pressures (see Fig. in ESI) and with the equalization of bonds at HP and the anomalous increase of the short bond distance at HP experimentally reported along the A7-to-Ah PT in elemental phosphorous . Interestingly, the equalization of bond distances between primary covalent bonds and secondary weak close-shell interactions upon the increase of pressure or density was already commented in relation to the formation of multicenter bonds in molecules and an anomalous increase in the covalent bond distance was observed in the region close to the formation of the multicenter bond . Moreover, simulations of the effect of pressure on elemental nitrogen have reported an anomalous increase of the intramolecular N-N bond distance at HP .