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["Chun Li " <chun.li@mf.mpg.de>]

Hi, Abinit users,

 

Could everyone give me some advice on this COMMENT? Thanks a lot.

 

And one more question: Is it important or necessary to optimize the lattice parameters before the calculation of band structures? I use the following lines,

 

optcell 1

ionmov 3

ntime 10

dilatmx 1.1

ecutsm 0.5

 

But when I just set optcell=0, the warning message in the logfile indicate not enough ntime even when I set ntime=500. And when I set optcell=1 to perform optimization, there is always an error message indicate not enough dilatmx (but when I reset dilatmx to the value it suggested, it just suggests more large values).

 

Maybe someone can help me, many thanks to you in advance.

 

Chun Li

 

-----Original Message-----
From: Chun Li [mailto:chun.li@mf.mpg.de]
Sent: 2004年7月14日 10:07
To: forum@abinit.org
Subject: [abinit-forum] about the COMMENT

 

Dear Abinit users,

 

I am trying to calculate the total energy of a crystal, and defined the unit cell with 4 atoms. However, after calculation, I always find the following COMMENT in the logfile (colored lines):

 

symanal : COMMENT -

  The Bravais lattice determined only from the primitive

  vectors, bravais(1)=  6, is more symmetric

  than the real one, iholohedry=  3, obtained by taking into

  account the atomic positions.

 symspgr : the symmetry operation no.   1 is the identity

 symplanes : the symmetry operation no.   2 is a mirror plane

 symaxes : the symmetry operation no.   3 is a 2-axis

 symplanes : the symmetry operation no.   4 is a mirror plane

 symspgr : spgroup=  25  Pm m 2   (=C2v^1)

 inkpts: Sum of    1 k point weights is    1.000000

 

Does that mean the atomic positions I defined in the xred have not been used in the calculation? But why? I want to know if this COMMENT occurs, will the results still be reliable? If not, how to solve it then? Thanks a lot in advance.

 

The relative lines in my input file:

acell   6.1397 6.1397 9.8379               

angdeg  90 90 60

natom 4          

typat   2 1 2 1

xred                  0.0  0.0  0.0    

                        0.5  0.5  0.1079 

                        0.5  0.5  0.5041 

                        0.0  0.0  0.5681