1c     Correlation energy and potential as determined via the local
2c     density functional of Vosko, Wilk and Nusair (Can. J. of Phys. 58,
3c     1200 (1980)), functional II.
4*
5* $Id$
6*
7#define FNL_VWN_2
8#include "xc_vwn_a.fh"
9c
10c     Compute the function deltaEc(rs,zeta) function and its derivatives
11c     wrt rs and zeta for the spin-unrestricted case - the rest has the
12c     same form for all VWN functionals and is handled in the header files.
13c
14            dec_rsz = devwn_rsz + (dec_rs1-derpa_rs1)*fz
15            d1dec_rsz(1) = d1devwn_rsz(1) + (d1dec_rs1-d1derpa_rs1)*fz
16            d1dec_rsz(2) = d1devwn_rsz(2) + (dec_rs1-derpa_rs1)*d1fz
17#ifdef SECOND_DERIV
18            d2dec_rsz(1) = d2devwn_rsz(1) + (d2dec_rs1-d2derpa_rs1)*fz
19            d2dec_rsz(2) = d2devwn_rsz(2) + (d1dec_rs1-d1derpa_rs1)*d1fz
20            d2dec_rsz(3) = d2devwn_rsz(3) + (dec_rs1-derpa_rs1)*d2fz
21#endif
22#ifdef THIRD_DERIV
23            d3dec_rsz(1) = d3devwn_rsz(1) + (d3dec_rs1-d3derpa_rs1)*fz
24            d3dec_rsz(2) = d3devwn_rsz(2)
25     &                   + (d2dec_rs1-d2derpa_rs1)*d1fz
26            d3dec_rsz(3) = d3devwn_rsz(3)
27     &                   + (d1dec_rs1-d1derpa_rs1)*d2fz
28            d3dec_rsz(4) = d3devwn_rsz(4)
29     &                   + (dec_rs1-derpa_rs1)*d3fz
30#endif
31c
32#include "xc_vwn_b.fh"
33c
34#ifndef SECOND_DERIV
35#define SECOND_DERIV
36c
37c     Compile source again for the 2nd derivative case
38c
39#include "xc_vwn_2.F"
40#endif
41#ifndef THIRD_DERIV
42#define THIRD_DERIV
43c
44c     Compile source again for the 3rd derivative case
45c
46#include "xc_vwn_2.F"
47#endif
48