[Wien] minimization of positions

[Hem Chandra Kandpal]

Dear Wien Users, 

I am trying to optimize the positions of a ternary system.
Below I am giving full detail about that system
system is 
MnCoSn ( a = 4.258 Ang, c = 5.36) (Space group 186)
Mn (0 0 1/4)
Co (1/3 2/3 0.44=z1)
Ge (1/3 2/3 0.06=z2)

To optimize the  z parameters of Co (z1) and Ge (z2) atoms.
I am using PORT option as given in the manual.

Let me tell you one thing, my system positions are far away from the
solution, because this system is only reported as Ni2In  structure type
(space group 194) and I would like to minimize it in LiGaGe structure 
type (space group 186). In space group 186 each atom will have their 
own positions as given above. These positions I took from other ternary system. 

I follow this procedure 
1. runsp_lapw -ec 0.0001 -i 40 -r 15
2. runsp_lapw -cc 0.001 -i 40 -r 15
3. runsp_lapw -fc 1 -i 40 -r 15

then I Have edited case.inM file like this

PORT 2.0           # PORT/NEWT;  tolf (geom.opt. stops when F<;tolf) 
0.0 0.0 1.0 3.0    # Mn
0.0 0.0 1.0 1.0    # Co #PORT: delta1,2,3=precond., 4:Bondorder 
0.0 0.0 1.0 1.0    # Sn

when I start with ---> min -NI -i 4 -s 1 -j 'runsp_lapw -I -i 40 -fc 1.0 '  

It is running and my forces are very far from force criterion and at the 
end in my dayfile it writes line like this -->

##########################dayfile
:ENERGY convergence:  0 0 .0000525000000000
:CHARGE convergence:  0 0.0000 .0002335

>   stop
>   mini        (01:07:58) 0.070u 0.015s 0:00.08 100.0% 0+0k 0+0io 0pf+0w
 :WARNING, CURVATURE CONDITION FAILED
 :WARNING, S.Y WAS -0.304898817526764
 :WARNING: Step size reduced due to overlapping spheres -- check RMT
 :WARNING: Step size reduced due to overlapping spheres -- check RMT
############################################################

my forces are looking like --->

###########################################
:ENE  : ********** TOTAL ENERGY IN Ry =       -34925.629006

       TOTAL FORCE IN mRy/a.u. = |F|     Fx             Fy             Fz
:FOR001:   1.ATOM        114.688     0.000     0.000   114.688
:FOR002:   2.ATOM        992.576     0.000     0.000   -992.576
:FOR003:   3.ATOM       1776.551     0.000     0.000   1776.551

#############################################

Can anyone please explain me, what is the process to do such kind of 
minimization, am I doing the right way? and what to do if I see 
with iterations, forces are increasing on each atom and vice versa.

What is the criterion for choosing RMT values for such complicated 
(I mean without knowing exact positions) systems.



############################

In the begining, I thought, I am doing some thing wrong with 
my calculations. then I tried to check these steps (as given above for 
minimization) on a well reported system 

example LiGaGe  (a = 4.175, c = 6.783 Ang) 
	Li (0 0 1/4)
        Ga (1/3 2/3 0.06)
        Ge (1/3 273 0.44)

and it coverges without any error, in my dayfile 

#############################################
>   stop
>   mini        (16:09:10) 0.029u 0.009s 0:00.04 50.0%  0+0k 0+0io 0pf+0w

>   stop forces small, minimization stopped

>   relaxation steps summarized in LiGaGe_opt.scf_mini

>   relaxed structure and results in LiGaGe_opt.struct, scf, clmsum
##############################################


and in my third optimized scf file :

############################################# 
:ENE  : ********** TOTAL ENERGY IN Ry =       -16202.425763

       TOTAL FORCE IN mRy/a.u. = |F|     Fx             Fy             Fz
:FOR001:   1.ATOM          1.242          0.000          0.000    1.242
:FOR002:   2.ATOM          2.019          0.000          0.000    -2.019
:FOR003:   3.ATOM          0.428          0.000          0.000     0.428

############################################


If it is working for such stabilized system it should work for 
my unrelaxed system. I think somewhere I missing some points.

What would be the good option for such system either PORT 
or NEWT. Can I also edit DELTA values (range???) in my 
case.inM file with PORT option like Prof. Blaha expalined
for NEWT in FAQ of Wien. 


I will be grateful for your kind reply and help

Thanking you in advance 
hem kandpal (mainz)