  Some exact and approximate methods commonly used to calculate corrections to
the Bethe stopping formula are modified and adapted by the authors to the
calculation of the energy loss straggling. An intercomparison is carried out
for results of approaches developed in the present work. An excellent agreement
obtained between the results for ELS, calculated with an exact method
previously proposed by one of the authors and the results of the
Lindhard-Sorensen method for moderate relativistic energies. It is shown that
some modified by authors approximate methods for the ELS calculating have the
higher accuracy than the conventional approximate method of
Lijian-Qing-Zhengming. So, in all the cases considered, the accuracy of the
twice modified LQZ method in the ELS calculations is higher than the accuracy
of the usual LQZ method. A thrice modified LQZ method was also suggested in
this work. A number of shortened LQZ methods for the ELS calculating have been
proposed and developed too.
