From 5df79c53745fde5d6c3340a2979b1429cd5892c1 Mon Sep 17 00:00:00 2001 From: Henrik Rydberg Date: Sat, 8 Oct 2011 20:30:28 +0200 Subject: Initial import of htcd system 1.0 Signed-off-by: Henrik Rydberg --- src/labat/ldaec.f | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 src/labat/ldaec.f (limited to 'src/labat/ldaec.f') diff --git a/src/labat/ldaec.f b/src/labat/ldaec.f new file mode 100644 index 0000000..01e18ca --- /dev/null +++ b/src/labat/ldaec.f @@ -0,0 +1,21 @@ + subroutine ldaec(rs,zet,ec) +c uniform-gas correlation of perdew and wang 1991 +c calculates the local correlation energy within the lda approx. +c input rs : seitz radius +c input zet : relative spin polarization +c output ec : correlation energy per electron + implicit double precision (a-h,o-z) + data gam,fzz/0.5198421d0,1.709921d0/ + data thrd4/1.333333333333d0/ + f = ((1.d0+zet)**thrd4+(1.d0-zet)**thrd4-2.d0)/gam + call gcor(0.0310907d0,0.21370d0,7.5957d0,3.5876d0,1.6382d0, + 1 0.49294d0,1.00d0,rs,eu,eurs) + call gcor(0.01554535d0,0.20548d0,14.1189d0,6.1977d0,3.3662d0, + 1 0.62517d0,1.00d0,rs,ep,eprs) + call gcor(0.0168869d0,0.11125d0,10.357d0,3.6231d0,0.88026d0, + 1 0.49671d0,1.00d0,rs,alfm,alfrsm) +c alfm is minus the spin stiffness alfc + z4 = zet**4 + ec = eu*(1.d0-f*z4)+ep*f*z4-alfm*f*(1.d0-z4)/fzz + return + end -- cgit v1.2.3