Gauge transformations of the conversion matrix elements

A problem is solved on what atomic subshells and at which transition multipolarities coefficients of internal conversion (CIC) are not dependent on a gauge constant G. Electrical CIC are not gauge-invariant on Ssub(1/2)- and Psub(1/2)-subshells at any transition multipolarity. On Psub(3/2)- or dsub(3/2)-subshells CIC are not dependent on the gauge option at L=1, but for all other L CIC invariance is violated. Three equivalent formulae for radial matrix element corresponding to a usual gauge G=√L(L+1) are presented. Comparison of CIC calculated with the help of three formulae may be used as a technique of verification of used approximations. Electrical CIC of the first two multipolarities were calculated for all Fe atom subshells at 1 keV energy above the ionization threshold. Calculations carried out using three presented formulae for radial matrix element gave the same CIC values in the limits of permissible errors of calculations