CASINO manual - Theory of Condensed Matter

-1 0 0 1
1 1 1 1
1 1 0 2
1 0 1 2
Parameter value ; Optimizable (0=NO; 1=YES)
END P TERM
START Q TERM
Spin dep (0->u=d; 1->u/=d)
0
Number of primitive-cell G-vectors (NB, cannot have both G & -G)
10
G-vector (in terms of rec latt vects) ; label
0 -1 1 -2
-1 1 0 -2
-1 0 1 -2
1 1 1 -1
-1 0 0 1
0 0 -1 1
0 -1 0 1
1 1 2 2
2 1 1 2
1 2 1 2
Parameter value ; Optimizable (0=NO; 1=YES)
END Q TERM
An alternative to the above u term is the so-called RPA form, whose syntax is as follows. Notice that
only one of the possible forms of u may be present in correlation.data. The use of the u RPA term
is not recommended in practice: lower energies and variances can be achieved using the standard u
term.
START U_RPA TERM
Number of sets
1
START SET 1
Spherical harmonic l,m
0 0
Spin dep (0->uu=dd=ud; 1->uu=dd/=ud; 2->uu/=dd/=ud)
1
Cutoff (a.u.) ; Optimizable (0=NO; 1=YES)
0.d0 1
Parameter values ; Optimizable (0=NO; 1=YES)
END SET 1
END U_RPA TERM
In homogeneous systems, a three-body W term can also be included:
START W TERM
Number of sets
1
START SET 1
Spherical harmonic l,m
0 0
Expansion order N_w
6
Spin dep (0->uu=dd=ud; 1->uu=dd/=ud; 2->uu/=dd/=ud)
0
Cutoff (a.u.) ; Optimizable (0=NO; 1=YES)
0.d0 1
Parameter values ; Optimizable (0=NO; 1=YES)
END SET 1
END W TERM
Alternatively, a more general three-body H term exists:
START H TERM
Number of sets
61