fortran gives strange results when writing to file - fortran

Question

I am using fortran. I want to write some information to a file, and here is my code:
open(unit=114514, position="append", file="msst_info.txt")
write(114514, 100) "step =", step
write(114514, 200) "A =", A
write(114514, 200) "omega =", omega(sd)
write(114514, 300) "dilation =", dilation(sd)
write(114514, 200) "p_msst =", p_msst / (kBar * 10)
write(114514, 300) "vol =", vol / Ang**3
write(114514, 300) "temp =", temperature
write(114514, 400) "+++++++++++++++++++++++++++"
100 format(A10, i8)
200 format(A10, e12.4)
300 format(A10, f12.4)
400 format(A)
close(114514)
I wish it can append the information to this file after each step. But the result is very strange:
dilation = 0.9999
p_msst = 0.3619E+02
vol = 10 A = -0.1041E-23
omega = -0.2290E-15
dilation = 0.9999
p_msst = 0.3619E+02
vol A = -0.1041E-23
omega = -0.2290E-15
dilation = 0.9999
p_msst = 0.3619E+02
vol = 1053.0452
temp = 195.9830
+++++++++++++++++++++++++++
step = 6
A = -0.1041E-23
omega = -0.2290E-15
dilation = 0.9999
p_msst = 0.3619E+02
vol = 1053.0452
temp = 195.9830
+++++++++++++++++++++++++++
step = 7
A = -0.1249E step = 7
A = -0.1249E-23
omega = -0.2290E-15
dilation = 0.9999
p_msst = 0.4342E+02
vol = 1052.8163
temp = 198.4668
+++++++++++++++++++++++++++
the format of step 6 is what i want. but in step 7, some text is written multiple times, and their position is completely wrong. I wonder why it happens.
the whole code:
module msst
use poscar_struct_def
use dynconstr
use prec
use reader_tags
use poscar
implicit none
contains
subroutine msst_step(dyn, latt_cur, t_info, tsif, tifor, io, niond, nionpd, ntypd, ntyppd)
! =======================================================================
! Written by S. Pan 2021/5/28
! This subroutine calculate a msst step. (Evan J. Reed 2003 PRL)
! I refer to fix_msst.cpp in LAMMPS when writing this code.
! The v(t-dt/2) is needed for velocity verlet algo.
! Two step: first, calculate the velocity v(t) with the a(t) and v(t-dt/2).
! second: give the position of ion and cell x(t+dt), and v(t+dt/2).
! The parameter mu is neglected since it makes the process complex.
! dyn: the struct for some MD variables, such as x, v, force.
! t_info: the struct for type information, such as number of ions.
! step: the current number of step. Init if step == 1.
! =======================================================================
! the dyn info will be changed
type(dynamics), intent(in out) :: dyn
type(latt), intent(in out) :: latt_cur
type(type_info), intent(in out) :: t_info
! these are inputs, should not be modified
type(in_struct), intent(in) :: io
real(q), dimension(3, t_info%nions), intent(in) :: tifor ! force on ions
real(q), dimension(3, 3), intent(in) :: tsif ! stress
! some units
real(q), parameter :: eV = 1.60218e-19, Ang = 1e-10, fs = 1e-15, &
amu = 1.66053886e-27, kBar = 1e5, kB = 1.38064852e-23
! energy in J, length in meter, time in s, mass in kg
! stress in Pa
! internal variables
real(q), save :: dt, dthalf, tscale, qmass, vs, total_mass=0, vol0
real(q), dimension(3, t_info%nions) :: velocity_before_half_dt, velocity_now, velocity_after_half_dt, &
C_force, x
real(q), dimension(3), save :: omega = [0, 0, 0] ! the time derivative of cell
real(q), dimension(3) :: dilation = [1, 1, 1]
integer :: ierr, ii, ni, nt, niond, nionpd, ntypd, ntyppd
integer, save :: sd, step = 0
real(q), dimension(3, 3) :: kinetic_stress, total_stress
real(q), dimension(3, 3), save :: p0
real(q) :: p_msst, A, vol, vol1, vol2, fac1, sqrt_initial_temperature_scaling, temperature, ekin
if (step .eq. 0) then
dyn%init = 0
call rd_poscar(latt_cur, t_info, dyn, &
& niond, nionpd, ntypd, ntyppd, &
& io%iu0, io%iu6)
end if
dyn%posioc = dyn%posion
step = step + 1
dt = dyn%potim * fs
dthalf = dt/2
! convert x to cartsian coordination. x and velocity use standard unit.
do ii = 1, 3
x(ii, :) = dyn%posion(ii, :) * latt_cur%a(ii, ii) * Ang
end do
! there isn't anything in dyn%pomass. so must use t_info%pomass
ni=1
do nt=1,t_info%ntyp
do ni=ni,t_info%nityp(nt)+ni-1
C_force(:, ni) = tifor(:, ni)/t_info%pomass(nt)
total_mass = total_mass + t_info%pomass(nt)
enddo
enddo
C_force = C_force * (eV/Ang/amu)
total_mass = total_mass * amu
if (step .eq. 1) then
! read these tags from INCAR
call process_incar(io%lopen, io%iu0, io%iu5, 'qmass', qmass, ierr, .true.)
call process_incar(io%lopen, io%iu0, io%iu5, 'tscale', tscale, ierr, .true.)
call process_incar(io%lopen, io%iu0, io%iu5, 'shock_direction', sd, ierr, .true.)
call process_incar(io%lopen, io%iu0, io%iu5, 'shock_velocity', vs, ierr, .true.)
! use tscale to give a initial cell velocity, or the cell will stay still forever
do ii = 1, 3
velocity_now(ii, :) = dyn%vel(ii, :) * latt_cur%a(ii, ii) * (Ang/fs) / dyn%potim
end do
CALL EKINC(EKIN,T_INFO%NIONS,T_INFO%NTYP,T_INFO%ITYP,T_INFO%POMASS,DYN%POTIM,LATT_CUR%A,DYN%VEL)
temperature = 2 * ekin * eV / (kB * t_info%nions * 3 )
fac1 = tscale*total_mass/qmass*temperature
omega(sd) = -sqrt(fac1)
sqrt_initial_temperature_scaling = sqrt(1.0-tscale)
velocity_now = velocity_now * sqrt_initial_temperature_scaling
else
! =======================================================================
! 2nd half of Verlet update. this part get current velocity from t-dt/2.
! =======================================================================
! propagate particle velocities 1/2 step, it should not be done on the first step of MD.
do ii = 1, 3
velocity_before_half_dt(ii, :) = dyn%vel(ii, :) * latt_cur%a(ii, ii) * (Ang/fs) / dyn%potim
end do
velocity_now = velocity_before_half_dt + C_force*dthalf
end if
! compute new pressure and volume and temperature
call compute_kinetic_stress(t_info, latt_cur, dyn, kinetic_stress, tsif, -1)
total_stress = tsif + kinetic_stress
total_stress = total_stress * kBar
vol = latt_cur%a(1, 1) * latt_cur%a(2, 2) * latt_cur%a(3, 3) * (Ang**3)
if (step .eq. 1) then
p0 = total_stress
vol0 = vol
end if
p_msst = vs**2 * total_mass * (vol0 - vol)/vol0**2
A = total_mass * (total_stress(sd, sd) - p0(sd, sd) - p_msst) / qmass
! qmass is in mass(kg)**2 / length(m)**4
if (step .ne. 1) then
! propagate the time derivative of the volume 1/2 step at fixed V, r, rdot
! it should not be done on the first step of MD.
omega(sd) = omega(sd) + A*dthalf ! this is the current omega
end if
! =======================================================================
! 1st half of Verlet update
! in VASP, the 1st half of Verlet update cannot be performed before
! compute force and stress. So it must be placed here.
! =======================================================================
! propagate the time derivative of the volume 1/2 step at fixed vol, r, rdot
omega(sd) = omega(sd) + A*dthalf ! this is omega(t+dt/2)
! propagate velocities 1/2 step
velocity_after_half_dt = velocity_now + C_force*dthalf
! now, we need to compute the vol and pos for next step:
! propagate the volume 1/2 step
vol1 = vol + omega(sd)*dthalf
! rescale positions and change box size
dilation(sd) = vol1/vol
call remap(latt_cur, sd, x, velocity_after_half_dt, dilation,t_info)
! propagate particle positions 1 time step
x = x + dt * velocity_after_half_dt
! propagate the volume 1/2 step
vol2 = vol1 + omega(sd)*dthalf
! rescale positions and change box size
dilation(sd) = vol2/vol1
call remap(latt_cur, sd, x, velocity_after_half_dt, dilation,t_info)
do ii = 1, 3
dyn%posion(ii, :) = x(ii, :) / latt_cur%a(ii, ii) / Ang
dyn%vel(ii, :) = velocity_after_half_dt(ii, :) / latt_cur%a(ii, ii) / (Ang/fs) * dyn%potim
end do
t_info%posion = dyn%posion
CALL EKINC(EKIN,T_INFO%NIONS,T_INFO%NTYP,T_INFO%ITYP,T_INFO%POMASS,DYN%POTIM,LATT_CUR%A,DYN%VEL)
temperature = 2 * ekin * eV / (kB * t_info%nions * 3 )
! this block for debug. write the information to a file
if (.true.) then
open(unit=114514, position="append", file="msst_info.txt")
write(114514, 100) "step =", step
write(114514, 200) "A =", A
write(114514, 200) "omega =", omega(sd)
write(114514, 300) "dilation =", dilation(sd)
write(114514, 200) "p_msst =", p_msst / (kBar * 10)
write(114514, 300) "vol =", vol / Ang**3
write(114514, 300) "temp =", temperature
write(114514, 400) "+++++++++++++++++++++++++++"
100 format(A10, i8)
200 format(A10, e12.4)
300 format(A10, f12.4)
400 format(A)
close(114514)
end if
end subroutine msst_step
! change the shape of cell, along with ion pos and vel.
subroutine remap(latt_cur, sd, x, v, dilation,t_info)
integer, intent(in):: sd
type(type_info), intent(in) :: t_info
real(q), dimension(3), intent(in) :: dilation
real(q), dimension(3, t_info%nions), intent(in out) :: x, v
type(latt), intent(in out) :: latt_cur
latt_cur%a(sd, sd) = dilation(sd) * latt_cur%a(sd, sd)
x(sd, :) = dilation(sd) * x(sd, :)
v(sd, :) = dilation(sd) * v(sd, :)
end subroutine remap
end module msst