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[Enrico <enrico.avenati@yahoo.com>]

Hi, i've some questions

1) I'm trying to get the entahlpies of formation of Cu-Dy compounds. 

I'm using TM psp cause they are the only ones to reach convergence at least 
for
compounds as CuDy (cP2)   Cu5Dy(cF24 - hP6).

i can't relax Dy hP2 or at least if the calulation ends i do have many
WARNINGs!!!

Anyways if I try to find the enthalpy, let's say of Cu5Dy hP6

i got ALWAYS positive result 43,30282623 Ha.

And this result is COMMON for ALL the structure, i don't understand what is
wrong. 
I did it already on many compounds and got always good result.

Do you have any idea?




2) i would like to know how i should manage the RPRIM variation in BCC
structure to find ACELL parameters.

I've notice it changed from 0.5 to 0.57xx. 

Should i do as for the FCC? = 2 * rprim*acell ( as I was suggetsted)


THANK YOU IN ADVANCE FoR YOUR HELP

Enrico 

MY INPUT are

#Dy hcp

acell 2*6.838 11.2

rprim # funz. anche con ANGDEG
1 0 0 
-0.5 sqrt(0.75) 0
0 0 1

#spcgrp 194 

ntypat 1
znucl  66
natom  2  # atom per cell
typat  1 1  # this atom is of type 1 
xred 
1/3 2/3 1/4 
2/3 1/3 3/4 #2c

#GEOM OPTIMISATION
optcell 2   # optimisation of volume only & ....
ionmov  3   # conduct structural optimization using the
Broyden-Fletcher-Goldfarb-Shanno minimization (BFGS),
            #   modified to take into account the total energy as well as the
gradients (as in usual BFGS)
ntime  100
dilatmx 1.1   # the maximal permitted scaling of the lattice parameters when
the cell shape and dimension is varied 
ecutsm  0.5    # Using a non-zero ecutsm, the total energy curves as a 
function
of ecut, or acell,
                 can be smoothed, keeping consistency with the stress


#RECIPROCAL SPACE INTEGRETION
kptopt 1
ngkpt 3 3 3
nband 16
tsmear 0.02
occopt 4

#PLANE WAVES
ecut 100

#SCF PROCEDURE
nstep 500
ixc 1
toldfe 1.0d-7

and  beta-Cu5Dy (hp6), I'm trying a full relaxation right now


#Cu5Dy hP6


acell 9.8485363353 9.8485363353 7.8788290683

rprim 
1 0 0 
-0.5 sqrt(0.75) 0
0 0 1

ntypat 2

znucl  29 66

natom  6  # atom per cell

typat  2 5*1  # 5*1 Cu

xred # missing in Villars & Calvert
0.0 0.0 0.0    # 1a Dy
1/3 2/3 0.0    # 2c Cu
2/3 1/3 0.0
1/2 0.0 1/2    # 3g Cu
0.0 1/2 1/2
1/2 1/2 1/2
 
#GEOM OPTIMISATION
optcell 1   # optimisation of volume & ...
ionmov  3   # conduct structural optimization using the
Broyden-Fletcher-Goldfarb-Shanno minimization (BFGS),
            #   modified to take into account the total energy as well as the
gradients (as in usual BFGS)
ntime  30
dilatmx 1.05   # the maximal permitted scaling of the lattice parameters when
the cell shape and dimension is varied 
ecutsm  0.5    # Using a non-zero ecutsm, the total energy curves as a 
function
of ecut, or acell,
                 can be smoothed, keeping consistency with the stress


#RECIPROCAL SPACE INTEGRETION
kptopt 1
ngkpt 3 3 3

nshiftk 1
shiftk 0.0 0.0 0.5

nband 40
tsmear 0.02
occopt 4

#PLANE WAVES
ecut 200


#SCF PROCEDURE
nstep 500
ixc 1
toldfe 1.0d-7

Cu5Dy cF24 gives  the SAME ENERGY DIFFERENCE TOO. 

#Cu5Dy cF24

acell  3*7.2 Angstr
rprim  0.0  0.5  0.5   # Real space PRIMitive translations
       0.5  0.0  0.5 
       0.5  0.5  0.0

ntypat 2
znucl  29 66
natom  6  # atom per cell
typat  1 1 1 1 1 2  # 5*1 Cu
xred
0.0 0.0 0.0    # 4a  TRASNSFORM with rprim inverse matrix
5/8 5/8 5/8    #16e
-7/8 5/8 5/8   # x -x -x
5/8 -7/8 5/8   # -x x -x 
5/8 5/8 -7/8  # -x -x x
1/4 1/4 1/4    # 4c Dy


#GEOM OPTIMISATION
optcell 2   # optimisation of volume & ...
ionmov  3   # conduct structural optimization using the
Broyden-Fletcher-Goldfarb-Shanno minimization (BFGS),
            #   modified to take into account the total energy as well as the
gradients (as in usual BFGS)
ntime  50
dilatmx 1.05   # the maximal permitted scaling of the lattice parameters when
the cell shape and dimension is varied 
ecutsm  0.5    # Using a non-zero ecutsm, the total energy curves as a 
function
of ecut, or acell,
                 can be smoothed, keeping consistency with the stress


#RECIPROCAL SPACE INTEGRETION
kptopt 1
ngkpt 3 3 3

nshiftk 4            # shiftk=4 particular efficient for FCC 
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5

nband 40
tsmear 0.02
occopt 4

#PLANE WAVES
ecut 200


#SCF PROCEDURE
nstep 500
ixc 1
toldfe 1.0d-7