Example mcphas.j file for a simple antiferromagnet

Here are example files of a tetragonal antiferromagnet with nearest neighbour interactions, all files are equivalent:

 
# simple antiferromagnet 
#<!--mcphase.mcphas.j-->
#***************************************************************
# Lattice Constants (A)
#! a=4.3843 b=4.3843 c=2.4194 alpha=  90 beta=  90 gamma=  90
#! r1a=   1 r2a=   0 r3a=   0
#! r1b=   0 r2b=   1 r3b=   0   primitive lattice vectors [a][b][c]
#! r1c=   0 r2c=   0 r3c=   1
#! nofatoms=1  nofcomponents=3  number of atoms in primitive unit cell/number of components of each spin
# ****************************************************************************
#! da=  0 [a] db=  0 [b] dc=  0 nofneighbours=2 diagonalexchange=0  sipffilename=Ce3p.sipf
# da[a] db[b] dc[c] Jaa[meV] Jbb[meV] Jcc[meV] Jab[meV] Jba[meV] Jac[meV] Jca[meV] Jbc[meV] Jcb[meV]
+0	+0	+1	-0.1	-0.1	-0.1   0  0  0  0  0  0
+0	+0	-1	-0.1	-0.1	-0.1   0  0  0  0  0  0
#

Using diagonalexchange this may be shortened to

 
# simple antiferromagnet 
#<!--mcphase.mcphas.j-->
#***************************************************************
# Lattice Constants (A)
#! a=4.3843 b=4.3843 c=2.4194 alpha=  90 beta=  90 gamma=  90
#! r1a=   1 r2a=   0 r3a=   0
#! r1b=   0 r2b=   1 r3b=   0   primitive lattice vectors [a][b][c]
#! r1c=   0 r2c=   0 r3c=   1
#! nofatoms=1  nofcomponents=3  number of atoms in primitive unit cell/number of components of each spin
# ****************************************************************************
#! da=  0 [a] db=  0 [b] dc=  0 nofneighbours=2 diagonalexchange=1  sipffilename=Ce3p.sipf
# da[a] db[b] dc[c] Jaa[meV] Jbb[meV] Jcc[meV] Jab[meV] Jba[meV] Jac[meV] Jca[meV] Jbc[meV] Jcb[meV]
+0	+0	+1	-0.1	-0.1	-0.1   
+0	+0	-1	-0.1	-0.1	-0.1   
#

with indexexchange option the sequence of two ion interaction parameters can be changed and zero parameters may be omitted:

 
# simple antiferromagnet 
#<!--mcphase.mcphas.j-->
#***************************************************************
# Lattice Constants (A)
#! a=4.3843 b=4.3843 c=2.4194 alpha=  90 beta=  90 gamma=  90
#! r1a=   1 r2a=   0 r3a=   0
#! r1b=   0 r2b=   1 r3b=   0   primitive lattice vectors [a][b][c]
#! r1c=   0 r2c=   0 r3c=   1
#! nofatoms=1  nofcomponents=3  number of atoms in primitive unit cell/number of components of each spin
# ****************************************************************************
#! da=  0 [a] db=  0 [b] dc=  0 nofneighbours=2 diagonalexchange=2  sipffilename=Ce3p.sipf
# da[a] db[b] dc[c] Jaa[meV] Jbb[meV] Jcc[meV] Jab[meV] Jba[meV] Jac[meV] Jca[meV] Jbc[meV] Jcb[meV]
#! indexexchange = JaJa JaJc JcJa JbJb JcJc
+0	+0	+1	-0.1 0 0 -0.1	-0.1  
+0	+0	-1	-0.1 0 0 -0.1	-0.1  
#

 
# simple antiferromagnet 
#<!--mcphase.mcphas.j-->
#***************************************************************
# Lattice Constants (A)
#! a=4.3843 b=4.3843 c=2.4194 alpha=  90 beta=  90 gamma=  90
#! r1a=   1 r2a=   0 r3a=   0
#! r1b=   0 r2b=   1 r3b=   0   primitive lattice vectors [a][b][c]
#! r1c=   0 r2c=   0 r3c=   1
#! nofatoms=1  nofcomponents=3  number of atoms in primitive unit cell/number of components of each spin
# ****************************************************************************
#! da=  0 [a] db=  0 [b] dc=  0 nofneighbours=2 diagonalexchange=2 sipffilename=Ce3p.sipf
# da[a] db[b] dc[c] Jaa[meV] Jbb[meV] Jcc[meV] Jab[meV] Jba[meV] Jac[meV] Jca[meV] Jbc[meV] Jcb[meV]
#! indexexchange = 1,1 1,3, 3,1 2,2 3,3
+0	+0	+1	-0.1 0 0 -0.1	-0.1  
+0	+0	-1	-0.1 0 0 -0.1	-0.1  
#

using symmetricexchange together with indexexchange will assume that the interaction tensor is symmetic and only half of it may be given:

 
# simple antiferromagnet 
#<!--mcphase.mcphas.j-->
#***************************************************************
# Lattice Constants (A)
#! a=4.3843 b=4.3843 c=2.4194 alpha=  90 beta=  90 gamma=  90
#! r1a=   1 r2a=   0 r3a=   0
#! r1b=   0 r2b=   1 r3b=   0   primitive lattice vectors [a][b][c]
#! r1c=   0 r2c=   0 r3c=   1
#! nofatoms=1  nofcomponents=3  number of atoms in primitive unit cell/number of components of each spin
# ****************************************************************************
#! da=  0 [a] db=  0 [b] dc=  0 nofneighbours=2 diagonalexchange=2 sipffilename=Ce3p.sipf
# da[a] db[b] dc[c] Jaa[meV] Jbb[meV] Jcc[meV] Jab[meV] Jba[meV] Jac[meV] Jca[meV] Jbc[meV] Jcb[meV]
#! symmetricexchange=1 indexexchange = JaJa JaJc JbJb JcJc
+0	+0	+1	-0.1 0  -0.1	-0.1  
+0	+0	-1	-0.1 0  -0.1	-0.1  
#



Martin Rotter 2017-01-10