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[myid520@hotmail.com]

Dear ABINIT users:
I’m calculating the lonsdaleite phases of si which has the same structure as 
wurtzite with the crystallographic symmetry of P63/mmc. Unfortunately when I 
wanted to get the lattice constant through Geometry Optimization, the error 
occurred and given the following log: 
#################################################################
chkdilatmx: ERROR -
  The new primitive vectors rprimd (an evolving quantity)
  are too large with respect to the old rprimd and the accompanying dilatmx :
  this large change of unit cell parameters is not allowed by the present 
value of dilatmx.
  You need at least dilatmx=    1.760168E+00
  Action : increase the input variable dilatmx.
##################################################################
The Pseudopotential I used is Troullier-Martins pseudopotentials.The 
following id the input file.
##########################################
# Crystalline silicon : lonsdaleite
ecut 15.0        
#Optimization of the lattice parameters
optcell 1
ionmov  3
ntime  30
dilatmx 1.05
ecutsm  0.5
tolmxf 5.0d-5
#Definition of the k-point grids
kptopt 1          
nshiftk 1
shiftk     0.0 0.0 0.5
ngkpt  2 2 2   
acell 2*7.16  11.84
rprim  0.86602540378   0.5  0.0  
       -0.86602540378  0.5  0.0   
       0.0  0.0  1.0
#Definition of the atom types
ntype 1           # There is only one type of atom
znucl 14         
#Definition of the atoms
natom 8          
type 8*1         
xred    3.3333333333E-01  6.6666666667E-01  0.0000000000E+00
        3.3333333333E-01  6.6666666667E-01  1.2500000000E-01
        3.3333333333E-01  6.6666666667E-01  3.7500000000E-01
        3.3333333333E-01  6.6666666667E-01  5.0000000000E-01
        6.6666666667E-01  3.3333333333E-01  5.0000000000E-01
        6.6666666667E-01  3.3333333333E-01  6.2500000000E-01
        6.6666666667E-01  3.3333333333E-01  8.7500000000E-01
        6.6666666667E-01  3.3333333333E-01  1.0000000000E+00
#xcart  -2.0669139637 3.58 0.0   
        -2.0669139637 3.58 1.48     
        -2.0669139637 3.58 4.44
        -2.0669139637 3.58 5.92
        2.0669139637 3.58 5.92
        2.0669139637 3.58 7.4
        2.0669139637 3.58 10.36
        2.0669139637 3.58 11.84
 chkprim  0
#Definition of the SCF procedure
nstep 30          
toldff 5.0d-6     
diemac 12.0       
####################################################################

Do you have any suggestion for making this optimization succeeding?
Thanks in advance!   
                      Zhenhua Zeng