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[James Raynolds <JRaynolds@uamail.albany.edu>]

Everyone,

        A better way to calculate the surface energy is to calculate the
adhesion energy curve for two slabs vs. distance.  The surface energy is
then 1/2 the depth of the curve (i.e. 1/2 of the energy at the minimum).
You will find that the surface energy converges extremely rapidly: i.e.
within 3 to 4 atomic layers  per slab.  The reason for this is that you are
taking advantage of cancellation of errors.  

Jim Raynolds

-----Original Message-----
From: myid520@hotmail.com [mailto:myid520@hotmail.com]
Sent: Friday, July 18, 2003 5:23 AM
To: forum@abinit.org
Subject: [abinit-forum] surface energy of aluminum (111) orientation!


Hello everyone:
    The following is the result and  input file of the calculation of the
surface energy of aluminum (111) orientation with 3 

vacuum layers. the result is:

aluminum laters       surface energy
 
  2                     0.3975  
  3                     0.3810  
  4                     0.4282  
  5                     0.4426  
  6                     0.4409  
  7                     0.4294  
  8                     0.4278  
  9                     0.4294  
  10                    0.4314  
  11                    0.4305  
  12                    0.4312  
  13                    0.4301  
  14                    0.4303  
  15                    0.4295  
  16                    0.4295  
  17                    0.4291  
  18                    0.4293  
  19                    0.4289  
  20                    0.4294  
  21                    0.4285
        
I don't known why the surface energy is low at beginning. I hope someone can
help me !

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＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃

＃ the input file
# 3 vacuum 
ndtset 20
occopt 4
tsmear 0.04
#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetries
ngkpt  4 4 4  
nshiftk 1
shiftk 0.0 0.0 0.5

#Definition of the unit cell
acell 2*5.3072542222 13.0000647796
rprim:    1.0000000000E+00  0.0000000000E+00  0.0000000000E+00
         -5.0000000000E-01  8.6602540378E-01  0.0000000000E+00
          0.0               0.0               1.6666666667
rprim+  0.0 0.0 0.0
        0.0 0.0 0.0
        0.0 0.0 0.3333333333
 
#Definition of the atom types
ntype 1           
zatnum 13         
ecutsm  0.5
nband: 4
nband+ 2 
#Definition of the atoms
chkprim  0
natom: 2
natom+ 1           # There are two atoms in this doubled cell
type 21*1          # These atoms are of type 1, that is, Aluminum
xcart            
        3*0.0                                           #1
        2.6536271111   1.5320723269  4.33335492654      #2   
        0.0            3.0641446538  8.6667098531       #3
        2*0.0          13.0000647796                   #4
        2.6536271111   1.5320723269  17.3334197062     #5
        0.0            3.0641446538  21.6667746327     #6
        2*0.0          26.0001295592                   #7
        2.6536271111   1.5320723269  30.3334844858   #8  
        0.0            3.0641446538  34.6668394123   #9
        2*0.0          39.0001943389                 #10
        2.6536271111   1.5320723269   43.3335492654  #11
        0.0            3.0641446538   47.6669041919  #12
        2*0.0          52.0002591185                 #13
        2.6536271111   1.5320723269   56.3336140450  #14
        0.0            3.0641446538   60.6669689716  #15
        2*0.0          65.0003238981                 #16
        2.6536271111   1.5320723269   69.33367882464 #17
        0.0            3.0641446538   73.66703375118 #18
        2*0.0          78.00038867772                #19
        2.6536271111   1.5320723269  82.33374360426  #20
        0.0            3.0641446538  86.6670985308   #21
#definition of the planewave basis set
ecut  6.0         

#Definition of the SCF procedure
nstep 25          
toldfe 1.0d-6
iprcel 45