[Wien] RKmax in Wien2k NCM

[Fecher, Gerhard]

Hallo Peter or anyone else who has an idea,
I have a "problem" in the NCM Version, I need to reduce RKmax down to 4.0, otherwise I receive segmentation faults from lapw1.
(probably during allocation or reallocation in modules.F,  INIT_MATRICES)
I needed to set NMATMAX = 128 000 that RKmax=4.0 works, but 5.0 crashes already for a 14 atom system.
(Note in the regular (not ncm) 23.2 version the systems run with NMATMAX = 29 000 at RKmax=7.0)

How can I determine easily how large NMATMAX should be for a given matrix size and memory?
The manual tells: "(..., should be chosen according to the memory of your hardware, see chapter 11.2.3!)
As mentioned for the regular version in 11.2.3 NMATMAX is reduced by sqrt(2), I am not shure whether or not this holds in ncm that uses only lapw1c.
As seen below a matrix size of 840 works at NKMAX=128000 in the NCM version, whreas 1100 is already too large.
In the regular version NKMAX=29000 works for a matric size of aboz 2400 (most probably also for much larger size).

Or is there any other possibility to use larger RKmax, maybe by changing something in the code.

PS.: Just for info, I have between 3 and 4GB RAM per core available on each node.

PSS: Examples: for pure Fe, rkmax=8.0 works (2 atoms in the conventional cell),
     for a system with 14 atoms (Sr2FeO4) I need to lower RKmax to 4.0 because 4.5 crashes already
     whereas the regular lapw1 runs with at least 3 times larger matrix size at a quarter of NKMAX.

Some numbers for the 14 atom case
* Regular Version: NKMAX =  29000
RKmax=7.0 MATRIX SIZE  1606 LOs:  96  RKM= 6.99 (has inversion, not complex, lapw1)
RKmax=8.0 MATRIX SIZE  2388 LOs:  96  RKM= 8.00
* NCM Version: NKMAX = 128000
RKmax=4.0: MATRIX SIZE  840 LOs: 196  RKM= 3.98 has NO problem (always complex, lapw1c of NCM)
RKmax=4.5: MATRIX SIZE 1100 LOs: 196  RKM= 4.44 crashes for sequential and k-parallel
RKmax=5.0: MATRIX SIZE 1408 LOs: 196  RKM= 4.99 crashes

for comparison pure Fe (NCM Version mit NKMAX = 128000) runs with RKmax up to 8.0 without problems
RKmax=5.0: MATRIX SIZE  104 in the ncm Version (conventional cell, 2 atoms)
RKmax=6.0: MATRIX SIZE  118 LOs:  52  RKM= 5.42
RKmax=7.0: MATRIX SIZE  214
RKmax=8.0: MATRIX SIZE  238 LOs:  52  RKM= 7.66


Ciao
Gerhard