FLEX for Crystal field splitting

Executing flx in the directory CSF results in the following short help message
$[...\vert]$ flex_input_file [options]
Options:

-T	Temperature (0.001)
-U	Coulomb repulsion (1)
-Ns	Degeneracy of bands ((2))
-alpha	Mixing parameter (0.2)
-ph_reduce	Weather to screen PH diagrams with PP effective interaction (0)
-Na	Number of additional points around fermi function (50)
-si	Data will be read from standard input
-ph	Wheather to include PH-channel (1)
-pp	Wheather to include PP-channel (1)
-gw	Wheather to include GW-channel (1)
-gi	The input is green's function rather than spectral functions (0)

All parameters here have the same meaning as above except the parameter -gi is added and parameter Ns is more complicated to set properly. The case that we are able to treat with this simple peace of code is the case of crystal field splitted levels that have arbitrary degeneracy but they are not coupled through the off-diagonal elements of hybridization $\Delta$. A typical case is an $f$ shell that can acquire 7 electrons and is usually splitted into 6+6+2 multiplets. The input for Ns should than be -Ns "(6,6,2)". Note here that the quotation marks are required for every nonatomic expression for shell to interpret the input properly.

The example command line is as usual prepared in the CFS/work/history.flex and reads
../flx start/gloc.inp.210 -gi -U 4 -T 0.03 -Ns "(6,6,2)" -ph_reduce 1 -gi
In couple of second, the output is written in the file called sig.out that contains all nonequivalent self-energies (in this case three). In addition, there are also output files called Sigma.xxx. Each of them corresponds to one nonequivalent bath (Sigma.000 to the first bath, Sigma.001 to the second and so on) and contains the following information

• second column contains the real part of the input green's function
• third column contains the input spectral function
• fourth and fifth column is the total self-energy
• sixth column is the second order self-energy only
• seventh column is the particle hole ladder contribution only
• eighth column is the particle particle ladder contribution only
• ninth column is the gw contribution only