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lattice_U1.f
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lattice_U1.f
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program U1
C==========================================================================
C Preamble with useful definitions
C==========================================================================
include "par.f" ! file with all parameters
character(len=30) file_name, formatstring ! for output file
character :: cr ! for percentage loading
cr = char(13)
call cpu_time(start)
call ranstart
formatstring = "(A13,i2,A4)"
write(file_name, formatstring) "raw_data/dati",NX,".dat"
open(2, file=file_name, status='unknown') ! file for results
write(2,*) measures ! useful information for the analysis
write(2,*) beta
write(2,*) NX, NT
C==========================================================================
C Start simulation
C==========================================================================
call init()
call boundary()
print*, "Loop for tremalizzation..."
do k = 1, i_term
call metropolis()
enddo
print*, "Start of measurament..."
do i = 1, measures
write(*, '(A1)', advance='no') cr !I write cr needed to clean the shell
do j = 1, i_dec
call metropolis()
call over_relaxation()
call over_relaxation()
call over_relaxation()
call over_relaxation()
enddo
call charge(q)
write(2,*) q
!percentage loading
perc = i/float(measures)*100
write(*,'(f8.1, a2)', advance='NO') perc, " %"
flush(6)
enddo
C==========================================================================
C End of simulation
C==========================================================================
call ranfinish
write(*,*)
call cpu_time(finish)
time = finish-start
i_hr = time/3600 ! hour
imin = time/60 ! minutes
secd = mod(time, 60.0) ! seconds
write(*,'(i2, a3, i2, a3, f8.1, a3)')
& i_hr," h ", imin, " m ", secd, " s "
end program
c=========================================================================
C Initial condition : Random configuration
c=========================================================================
subroutine init()
include "par.f" ! file with all parameters
do j = 1, NX ! loop over lattice
do i = 1, NT
lv(i,j) = 1.0 - 2.*ran2()
lh(i,j) = 1.0 - 2.*ran2()
enddo
enddo
return
end
c=============================================================================
C Periodic boundary
c=============================================================================
subroutine boundary()
include "par.f" ! file with all parameters
integer, dimension(2) :: d
d = (/ NX, NT /) ! array of spatial and temporal extents
do j = 1, 2 ! loop over number of dimensions
do i = 1, d(j) ! loop over lattice
nl(i, j) = i + 1 ! nearest neighbors
ns(i, j) = i - 1
enddo
nl(d(j), j) = 1 ! fix boundary with
ns(1, j) = d(j) ! periodic conditions
enddo
return
end
c============================================================================
C METROPOLIS
c============================================================================
subroutine metropolis()
include "par.f" ! file with all parameters
complex :: c
c = (0.0, 1.) ! immaginary units
pi = 4 * atan(1.0) ! pi greco
do i_t = 1, NT ! loop over lattice
do i_s = 1, NX
C****************************** VERTICAL LINK *******************************
c_l = lv(i_t, i_s) ! value of current link
t_l = c_l + (ran2()*2. - 1.)*delta ! new trial value of link
f1 = - lh(i_t, i_s)
& - lv(i_t, nl(i_s, 1)) + lh(nl(i_t, 2), i_s) ! first staple
f2 = lh(i_t, ns(i_s, 1)) -
& lv(i_t, ns(i_s, 1)) - lh(nl(i_t, 2), ns(i_s, 1)) ! second staple
F_c = real(exp(c*(f1 + c_l)) + exp(c*(f2 + c_l))) ! current action
F_p = real(exp(c*(f1 + t_l)) + exp(c*(f2 + t_l))) ! trial action
r = beta*(F_p - F_c)
prob = log(ran2())
if (prob < r) then ! acceptance test
t_l = mod(t_l, 2.0*pi) ! the value must be
if (t_l < (-pi)) t_l = t_l + 2.0*pi ! between -pi and pi
if (t_l > pi) t_l = t_l - 2.0*pi
lv(i_t, i_s) = t_l ! update link
endif
C****************************** HORIZZONTAL LINK *******************************
c_l = lh(i_t, i_s) ! value of current link
t_l = c_l + (ran2()*2. - 1.)*delta ! new trial value of link
f1 = - lv(i_t,i_s)
& - lh(nl(i_t, 2), i_s) + lv(i_t, nl(i_s, 1)) ! frist staple
f2 = lv(ns(i_t, 2), i_s) - lh(ns(i_t, 2), i_s) - ! second staple
& lv(ns(i_t, 2), nl(i_s, 1))
F_c = real(exp(c*(f1 + c_l)) + exp(c*(f2 + c_l))) ! current action
F_p = real(exp(c*(f1 + t_l)) + exp(c*(f2 + t_l))) ! trial action
r = beta*(F_p - F_c)
prob = log(ran2())
if (prob < r) then ! acceptance test
t_l = mod(t_l, 2.0*pi) ! the value must be
if (t_l < (-pi)) t_l = t_l + 2.0*pi ! between -pi and pi
if (t_l > pi) t_l = t_l - 2.0*pi
lh(i_t, i_s) = t_l ! update link
endif
enddo
enddo
return
end
c============================================================================
C OVER RELAXATION
c============================================================================
subroutine over_relaxation()
include "par.f" ! file with all parameters
complex :: c, ff
c = (0.0, 1.) ! immaginary units
pi = 4 * atan(1.0) ! pi greco
do i_t = 1, NT ! loop over lattice
do i_s = 1, NX
C****************************** VERTICAL LINK *******************************
c_l = lv(i_t, i_s) ! value of current link
f1 = - lh(i_t, i_s)
& - lv(i_t, nl(i_s, 1)) + lh(nl(i_t, 2), i_s) ! first staple
f2 = lh(i_t, ns(i_s, 1)) -
& lv(i_t, ns(i_s, 1)) - lh(nl(i_t, 2), ns(i_s, 1)) ! second staple
ff = exp(-c*f1) + exp(-c*f2)
xf = imag(log(ff))
xf = mod(xf, 2.0*pi) ! the value must be
if (xf < (-pi)) xf = xf + 2.0*pi ! between -pi and pi
if (xf > pi) xf = xf - 2.0*pi
t_l = 2*xf - c_l
t_l = mod(t_l, 2.0*pi) ! the value must be
if (t_l < (-pi)) t_l = t_l + 2.0*pi ! between -pi and pi
if (t_l > pi) t_l = t_l - 2.0*pi
lv(i_t, i_s) = t_l ! update link
C****************************** HORIZZONTAL LINK *******************************
c_l = lh(i_t, i_s) ! value of current link
f1 = - lv(i_t,i_s)
& - lh(nl(i_t, 2), i_s) + lv(i_t, nl(i_s, 1)) ! first staple
f2 = lv(ns(i_t, 2), i_s) - lh(ns(i_t, 2), i_s) - ! second staple
& lv(ns(i_t, 2), nl(i_s, 1))
ff = exp(-c*f1) + exp(-c*f2)
xf = imag(log(ff))
xf = mod(xf, 2.0*pi) ! the value must be
if (xf < (-pi)) xf = xf + 2.0*pi ! between -pi and pi
if (xf > pi) xf = xf - 2.0*pi
t_l = 2*xf - c_l
t_l = mod(t_l, 2.0*pi) ! the value must be
if (t_l < (-pi)) t_l = t_l + 2.0*pi ! between -pi and pi
if (t_l > pi) t_l = t_l - 2.0*pi
lh(i_t, i_s) = t_l ! update link
enddo
enddo
return
end
c============================================================================
C Charge measurement
c============================================================================
subroutine charge(q)
include "par.f" ! file with all parameters
pi = 4 * atan(1.0) ! pi greco
q = 0.0 ! charge
plaq = 0.0 ! plaquette
do i_t = 1, NT ! loop over lattice
do i_s = 1, NX
square = lh(i_t, i_s) + lv(i_t, nl(i_s, 1)) -
& lh(nl(i_t, 2), i_s) - lv(i_t, i_s)
square = mod(square, 2.0*pi) ! the value must be
if (square < (-pi)) square = square + 2.0*pi ! between -pi and pi
if (square > pi ) square = square - 2.0*pi
plaq = plaq + square
enddo
enddo
q = int(plaq/(2.0*pi) + 0.1)
!q = int(plaq/(2.0*pi))
return
end
c============================================================================
c RANDOM NUMBER GENERATOR: standard ran2 from numerical recipes
c============================================================================
function ran2()
implicit real*4 (a-h,o-z)
implicit integer*4 (i-n)
integer idum,im1,im2,imm1,ia1,ia2,iq1,iq2,ir1,ir2,ntab,ndiv
real ran2,am,eps,rnmx
parameter(im1=2147483563,im2=2147483399,am=1./im1,imm1=im1-1,
& ia1=40014,ia2=40692,iq1=53668,iq2=52774,ir1=12211,
& ir2=3791,ntab=32,ndiv=1+imm1/ntab,eps=1.2e-7,
& rnmx=1.-eps)
integer idum2,j,k,iv,iy
common /dasav/ idum,idum2,iv(ntab),iy
c save iv,iy,idum2
c data idum2/123456789/, iv/NTAB*0/, iy/0/
if(idum.le.0) then
idum=max0(-idum,1)
idum2=idum
do j=ntab+8,1,-1
k=idum/iq1
idum=ia1*(idum-k*iq1)-k*ir1
if(idum.lt.0) idum=idum+im1
if(j.le.ntab) iv(j)=idum
enddo
iy=iv(1)
endif
k=idum/iq1
idum=ia1*(idum-k*iq1)-k*ir1
if(idum.lt.0) idum=idum+im1
k=idum2/iq2
idum2=ia2*(idum2-k*iq2)-k*ir2
if(idum2.lt.0) idum2=idum2+im2
j=1+iy/ndiv
iy=iv(j)-idum2
iv(j)=idum
if(iy.lt.1) iy=iy+imm1
ran2=min(am*iy,rnmx)
return
end
c=============================================================================
subroutine ranstart
implicit real*4 (a-h,o-z)
implicit integer*4 (i-n)
common /dasav/ idum,idum2,iv(32),iy
open(unit=23, file='randomseed', status='unknown')
read(23,*) idum
read(23,*,end=117) idum2
do i=1,32
read(23,*) iv(i)
enddo
read(23,*) iy
close(23)
goto 118 !!takes account of the first start
117 if(idum.ge.0) idum = -idum -1 !!
close(23)
118 continue !!
return
end
c=============================================================================
subroutine ranfinish
implicit real*4 (a-h,o-z)
implicit integer*4 (i-n)
common /dasav/ idum,idum2,iv(32),iy
open(unit=23, file='randomseed', status='unknown')
write(23,*) idum
write(23,*) idum2
do i=1,32
write(23,*) iv(i)
enddo
write(23,*) iy
close(23)
return
end
c=============================================================================