working on scan

src/dft_utils_one_e/ec_scan.irp.f

@@ -37,7 +37,8 @@ double precision function ec_scan(rho_a,rho_b,tau,grad_rho_2)
  gama     = 0.031091d0
  ! correlation energy lsda1
  call ec_only_lda_sr(0.d0,nup,ndo,e_c_lsda1)
-          
+ ! correlation energy per particle 
+ e_c_lsda1 = e_c_lsda1/rho         
  xi       = spin_d/rho
  rs       = (cst_43 * pi * rho)**(-cst_13)
  s        = drho/( 2.d0 * cst_3pi2**(cst_13) * rho**cst_43  )
@@ -61,7 +62,11 @@ double precision function ec_scan(rho_a,rho_b,tau,grad_rho_2)
  g_at2    = 1.d0/(1.d0 + 4.d0 * a*t*t)**0.25d0
  h1       = gama * phi_3 * dlog(1.d0 + w_1 * (1.d0 - g_at2))
  ! interpolation function 
- fc_alpha = dexp(-c_1c * alpha * inv_1alph) * step_f(cst_1alph) - d_c * dexp(c_2c * inv_1alph) * step_f(-cst_1alph) 
+ if(cst_1alph.gt.0.d0)then
+  fc_alpha = dexp(-c_1c * alpha * inv_1alph) 
+ else
+  fc_alpha = - d_c * dexp(c_2c * inv_1alph) 
+ endif
  ! first part of the correlation energy 
  e_c_1    = e_c_lsda1 + h1
  
@@ -82,19 +87,107 @@ double precision function ec_scan(rho_a,rho_b,tau,grad_rho_2)
  ec_scan = e_c_1 + fc_alpha * (e_c_0 - e_c_1)
 end
 
-double precision function step_f(x)
- implicit none
- double precision, intent(in) :: x
- if(x.lt.0.d0)then
-  step_f = 0.d0
- else
-  step_f = 1.d0 
- endif
-end             
-
 double precision function beta_rs(rs)
  implicit none
  double precision, intent(in) ::rs
  beta_rs(rs) = 0.066725d0 * (1.d0 + 0.1d0 * rs)/(1.d0 + 0.1778d0 * rs)
+!beta_rs(rs) = 0.066725d0 
 
 end
+
+double precision function ec_scan_print(rho_a,rho_b,tau,grad_rho_2)
+ include 'constants.include.F'
+ implicit none
+ double precision, intent(in) :: rho_a,rho_b,tau,grad_rho_2
+ double precision :: cst_13,cst_23,cst_43,cst_53,rho_inv,cst_18,cst_3pi2
+ double precision :: thr,nup,ndo,xi,s,spin_d,drho,drho2,rho,inv_1alph,e_c_lsda1,h0
+ double precision :: rs,t_w,t_unif,ds_xi,alpha,fc_alpha,step_f,cst_1alph,beta_inf
+ double precision :: c_1c,c_2c,d_c,e_c_ldsa1,h1,phi,t,beta_rs,gama,a,w_1,g_at2,phi_3,e_c_1
+ double precision :: b_1c,b_2c,b_3c,dx_xi,gc_xi,e_c_lsda0,w_0,g_inf,cx_xi,x_inf,f0,e_c_0
+ thr = 1.d-12
+ nup = max(rho_a,thr)
+ ndo = max(rho_b,thr)
+ rho = nup + ndo 
+ ec_scan_print = 0.d0
+ if((rho).lt.thr)return
+ ! constants ...
+ rho_inv  = 1.d0/rho
+ cst_13   = 1.d0/3.d0
+ cst_23   = 2.d0 * cst_13
+ cst_43   = 4.d0 * cst_13
+ cst_53   = 5.d0 * cst_13
+ cst_18   = 1.d0/8.d0
+ cst_3pi2 = 3.d0 * pi*pi
+ drho2    = max(grad_rho_2,thr)
+ drho     = dsqrt(drho2)
+ if((nup-ndo).gt.0.d0)then
+  spin_d  = max(nup-ndo,thr) 
+ else
+  spin_d  = min(nup-ndo,-thr) 
+ endif
+ c_1c     = 0.64d0
+ c_2c     = 1.5d0
+ d_c      = 0.7d0
+ b_1c     = 0.0285764d0
+ b_2c     = 0.0889d0
+ b_3c     = 0.125541d0
+ gama     = 0.031091d0
+ ! correlation energy lsda1
+ call ec_only_lda_sr(0.d0,nup,ndo,e_c_lsda1)
+ ! correlation energy per particle 
+ e_c_lsda1 = e_c_lsda1/rho         
+ xi       = spin_d/rho
+ rs       = (cst_43 * pi * rho)**(-cst_13)
+ s        = drho/( 2.d0 * cst_3pi2**(cst_13) * rho**cst_43  )
+ t_w      = drho2 * cst_18 * rho_inv
+ ds_xi    = 0.5d0 * ( (1.d0+xi)**cst_53 + (1.d0 - xi)**cst_53)
+ t_unif   = 0.3d0 * (cst_3pi2)**cst_23 * rho**cst_53*ds_xi
+ t_unif   = max(t_unif,thr)
+ alpha    = (tau - t_w)/t_unif
+ cst_1alph= 1.d0 - alpha
+ if(cst_1alph.gt.0.d0)then
+  cst_1alph= max(cst_1alph,thr)
+ else
+  cst_1alph= min(cst_1alph,-thr)
+ endif
+ inv_1alph= 1.d0/cst_1alph
+ phi      = 0.5d0 * ( (1.d0+xi)**cst_23 + (1.d0 - xi)**cst_23)
+ phi_3    = phi*phi*phi
+ t        = (cst_3pi2/16.d0)**cst_13 * s / (phi * rs**0.5d0)
+ w_1      = dexp(-e_c_lsda1/(gama * phi_3)) - 1.d0
+ a        = beta_rs(rs) /(gama * w_1)
+ g_at2    = 1.d0/(1.d0 + 4.d0 * a*t*t)**0.25d0
+ h1       = gama * phi_3 * dlog(1.d0 + w_1 * (1.d0 - g_at2))
+ print*,'w_1       g_at2 '
+ print*, w_1  ,    g_at2  
+ print*,'gama      phi_3      1.d0 + w_1 * (1.d0 - g_at2)'
+ print*, gama   ,  phi_3   ,  1.d0 + w_1 * (1.d0 - g_at2) 
+ ! interpolation function 
+ if(cst_1alph.gt.0.d0)then
+  fc_alpha = dexp(-c_1c * alpha * inv_1alph) 
+ else
+  fc_alpha = - d_c * dexp(c_2c * inv_1alph) 
+ endif
+ ! first part of the correlation energy 
+ e_c_1    = e_c_lsda1 + h1
+ print*,'e_c_lsda1      h1    '
+ print*, e_c_lsda1   ,  h1     
+ 
+ dx_xi    =  0.5d0 * ( (1.d0+xi)**cst_43 + (1.d0 - xi)**cst_43)
+ gc_xi    = (1.d0 - 2.3631d0 * (dx_xi - 1.d0) ) * (1.d0 - xi**12.d0)
+ e_c_lsda0= - b_1c / (1.d0 + b_2c * rs**0.5d0 + b_3c * rs)
+ w_0      = dexp(-e_c_lsda0/b_1c) - 1.d0
+ beta_inf = 0.066725d0 * 0.1d0 / 0.1778d0
+ cx_xi    = -3.d0/(4.d0*pi) * (9.d0 * pi/4.d0)**cst_13 * dx_xi
+
+ x_inf   = 0.128026d0
+ f0       = -0.9d0
+ g_inf    = 1.d0/(1.d0 + 4.d0 * x_inf * s*s)**0.25d0
+ 
+ h0       = b_1c * dlog(1.d0 + w_0 * (1.d0 - g_inf)) 
+ e_c_0    = (e_c_lsda0 + h0) * gc_xi
+
+ ec_scan_print = e_c_1 + fc_alpha * (e_c_0 - e_c_1)
+ write(*,*)'  e_c_1 , fc_alpha ,  e_c_0 '
+ write(*,*)   e_c_1 , fc_alpha ,  e_c_0  
+end