dR in Plane wave calculator

[Inaoton]

Hello Sir,
           Could you please tell me what is dR in log file of  plane wave calculator and what does it signify?

 0 E = -7.9122918660e+03   dE = -7.9122918660e+03   dR =  1.0008931677e-01  |
|   1 E = -7.9243780908e+03   dE = -1.2086224798e+01   dR =  3.1226745193e-01  |
|   2 E = -7.9167288926e+03   dE =  7.6491982706e+00   dR =  4.2047361767e-02  |
|   3 E = -7.9161336306e+03   dE =  5.9526196692e-01   dR =  1.8256674566e-02  |
|   4 E = -7.9160810406e+03   dE =  5.2590045130e-02   dR =  4.0077110455e-03  |
|   5 E = -7.9160766431e+03   dE =  4.3975129993e-03   dR =  2.0993319471e-03  |
|   6 E = -7.9160756709e+03   dE =  9.7217387884e-04   dR =  6.1107844535e-04  |
|   7 E = -7.9160756242e+03   dE =  4.6645614020e-05   dR =  4.8769945577e-04  |
|   8 E = -7.9160755741e+03   dE =  5.0144842135e-05   dR =  4.7447126024e-05  |
|   9 E = -7.9160755733e+03   dE =  7.8385255620e-07   dR =  1.5651633880e-05  |
|  10 E = -7.9160755732e+03   dE =  6.0288584791e-08   dR =  2.8880705820e-06  |
|  11 E = -7.9160755732e+03   dE =  1.2159944163e-09   dR =  3.8540388958e-07 

[Jess Wellendorff]

dR is the largest value of the difference between the electron density between two SCF steps. The dR is therefore supposed to decrease during the ATK-PW SCF loop, but is not an actual SCF convergence parameter (SCF convergence is determined by the total energy difference between SCF steps).