DAMASK_EICMD/src/phase_mechanical_plastic_di...

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!--------------------------------------------------------------------------------------------------
!> @author Franz Roters, Max-Planck-Institut für Eisenforschung GmbH
!> @author Philip Eisenlohr, Max-Planck-Institut für Eisenforschung GmbH
!> @author David Cereceda, Lawrence Livermore National Laboratory
!> @author Martin Diehl, Max-Planck-Institut für Eisenforschung GmbH
!> @brief crystal plasticity model for bcc metals, especially Tungsten
!--------------------------------------------------------------------------------------------------
submodule(phase:plastic) dislotungsten
real(pReal), parameter :: &
kB = 1.38e-23_pReal !< Boltzmann constant in J/Kelvin
type :: tParameters
real(pReal) :: &
D = 1.0_pReal, & !< grain size
mu = 1.0_pReal, & !< equivalent shear modulus
D_0 = 1.0_pReal, & !< prefactor for self-diffusion coefficient
Q_cl = 1.0_pReal !< activation energy for dislocation climb
real(pReal), allocatable, dimension(:) :: &
b_sl, & !< magnitude me Burgers vector [m]
D_a, &
i_sl, & !< Adj. parameter for distance between 2 forest dislocations
f_at, & !< factor to calculate atomic volume
tau_Peierls, & !< Peierls stress
!* mobility law parameters
Q_s, & !< activation energy for glide [J]
v_0, & !< dislocation velocity prefactor [m/s]
p, & !< p-exponent in glide velocity
q, & !< q-exponent in glide velocity
B, & !< friction coefficient
h, & !< height of the kink pair
w, & !< width of the kink pair
omega !< attempt frequency for kink pair nucleation
real(pReal), allocatable, dimension(:,:) :: &
h_sl_sl, & !< slip resistance from slip activity
forestProjection
real(pReal), allocatable, dimension(:,:,:) :: &
P_sl, &
nonSchmid_pos, &
nonSchmid_neg
integer :: &
sum_N_sl !< total number of active slip system
character(len=pStringLen), allocatable, dimension(:) :: &
output
logical :: &
dipoleFormation !< flag indicating consideration of dipole formation
end type !< container type for internal constitutive parameters
type :: tDisloTungstenState
real(pReal), dimension(:,:), pointer :: &
rho_mob, &
rho_dip, &
gamma_sl
end type tDisloTungstenState
type :: tDisloTungstendependentState
real(pReal), dimension(:,:), allocatable :: &
Lambda_sl, &
threshold_stress
end type tDisloTungstendependentState
!--------------------------------------------------------------------------------------------------
! containers for parameters and state
type(tParameters), allocatable, dimension(:) :: param
type(tDisloTungstenState), allocatable, dimension(:) :: &
dotState, &
state
type(tDisloTungstendependentState), allocatable, dimension(:) :: dependentState
contains
!--------------------------------------------------------------------------------------------------
!> @brief Perform module initialization.
!> @details reads in material parameters, allocates arrays, and does sanity checks
!--------------------------------------------------------------------------------------------------
module function plastic_dislotungsten_init() result(myPlasticity)
logical, dimension(:), allocatable :: myPlasticity
integer :: &
ph, i, &
Nconstituents, &
sizeState, sizeDotState, &
startIndex, endIndex
integer, dimension(:), allocatable :: &
N_sl
real(pReal),dimension(:), allocatable :: &
rho_mob_0, & !< initial dislocation density
rho_dip_0, & !< initial dipole density
a !< non-Schmid coefficients
character(len=pStringLen) :: &
extmsg = ''
class(tNode), pointer :: &
phases, &
phase, &
mech, &
pl
myPlasticity = plastic_active('dislotungsten')
if(count(myPlasticity) == 0) return
print'(/,a)', ' <<<+- phase:mechanical:plastic:dislotungsten init -+>>>'
print'(a,i0)', ' # phases: ',count(myPlasticity); flush(IO_STDOUT)
print*, 'Cereceda et al., International Journal of Plasticity 78:242256, 2016'
print*, 'https://dx.doi.org/10.1016/j.ijplas.2015.09.002'
phases => config_material%get('phase')
allocate(param(phases%length))
allocate(state(phases%length))
allocate(dotState(phases%length))
allocate(dependentState(phases%length))
do ph = 1, phases%length
if(.not. myPlasticity(ph)) cycle
associate(prm => param(ph), dot => dotState(ph), stt => state(ph), dst => dependentState(ph))
phase => phases%get(ph)
mech => phase%get('mechanics')
pl => mech%get('plasticity')
#if defined (__GFORTRAN__)
prm%output = output_asStrings(pl)
#else
prm%output = pl%get_asStrings('output',defaultVal=emptyStringArray)
#endif
! This data is read in already in lattice
prm%mu = lattice_mu(ph)
!--------------------------------------------------------------------------------------------------
! slip related parameters
N_sl = pl%get_asInts('N_sl',defaultVal=emptyIntArray)
prm%sum_N_sl = sum(abs(N_sl))
slipActive: if (prm%sum_N_sl > 0) then
prm%P_sl = lattice_SchmidMatrix_slip(N_sl,phase%get_asString('lattice'),&
phase%get_asFloat('c/a',defaultVal=0.0_pReal))
if(trim(phase%get_asString('lattice')) == 'cI') then
a = pl%get_asFloats('a_nonSchmid',defaultVal = emptyRealArray)
prm%nonSchmid_pos = lattice_nonSchmidMatrix(N_sl,a,+1)
prm%nonSchmid_neg = lattice_nonSchmidMatrix(N_sl,a,-1)
else
prm%nonSchmid_pos = prm%P_sl
prm%nonSchmid_neg = prm%P_sl
endif
prm%h_sl_sl = lattice_interaction_SlipBySlip(N_sl,pl%get_asFloats('h_sl_sl'), &
phase%get_asString('lattice'))
prm%forestProjection = lattice_forestProjection_edge(N_sl,phase%get_asString('lattice'),&
phase%get_asFloat('c/a',defaultVal=0.0_pReal))
prm%forestProjection = transpose(prm%forestProjection)
rho_mob_0 = pl%get_asFloats('rho_mob_0', requiredSize=size(N_sl))
rho_dip_0 = pl%get_asFloats('rho_dip_0', requiredSize=size(N_sl))
prm%v_0 = pl%get_asFloats('v_0', requiredSize=size(N_sl))
prm%b_sl = pl%get_asFloats('b_sl', requiredSize=size(N_sl))
prm%Q_s = pl%get_asFloats('Q_s', requiredSize=size(N_sl))
prm%i_sl = pl%get_asFloats('i_sl', requiredSize=size(N_sl))
prm%tau_Peierls = pl%get_asFloats('tau_Peierls', requiredSize=size(N_sl))
prm%p = pl%get_asFloats('p_sl', requiredSize=size(N_sl), &
defaultVal=[(1.0_pReal,i=1,size(N_sl))])
prm%q = pl%get_asFloats('q_sl', requiredSize=size(N_sl), &
defaultVal=[(1.0_pReal,i=1,size(N_sl))])
prm%h = pl%get_asFloats('h', requiredSize=size(N_sl))
prm%w = pl%get_asFloats('w', requiredSize=size(N_sl))
prm%omega = pl%get_asFloats('omega', requiredSize=size(N_sl))
prm%B = pl%get_asFloats('B', requiredSize=size(N_sl))
prm%D = pl%get_asFloat('D')
prm%D_0 = pl%get_asFloat('D_0')
prm%Q_cl = pl%get_asFloat('Q_cl')
prm%f_at = pl%get_asFloat('f_at') * prm%b_sl**3.0_pReal
prm%D_a = pl%get_asFloat('D_a') * prm%b_sl
prm%dipoleformation = .not. pl%get_asBool('no_dipole_formation', defaultVal = .false.)
! expand: family => system
rho_mob_0 = math_expand(rho_mob_0, N_sl)
rho_dip_0 = math_expand(rho_dip_0, N_sl)
prm%q = math_expand(prm%q, N_sl)
prm%p = math_expand(prm%p, N_sl)
prm%Q_s = math_expand(prm%Q_s, N_sl)
prm%b_sl = math_expand(prm%b_sl, N_sl)
prm%h = math_expand(prm%h, N_sl)
prm%w = math_expand(prm%w, N_sl)
prm%omega = math_expand(prm%omega, N_sl)
prm%tau_Peierls = math_expand(prm%tau_Peierls, N_sl)
prm%v_0 = math_expand(prm%v_0, N_sl)
prm%B = math_expand(prm%B, N_sl)
prm%i_sl = math_expand(prm%i_sl, N_sl)
prm%f_at = math_expand(prm%f_at, N_sl)
prm%D_a = math_expand(prm%D_a, N_sl)
! sanity checks
if ( prm%D_0 <= 0.0_pReal) extmsg = trim(extmsg)//' D_0'
if ( prm%Q_cl <= 0.0_pReal) extmsg = trim(extmsg)//' Q_cl'
if (any(rho_mob_0 < 0.0_pReal)) extmsg = trim(extmsg)//' rho_mob_0'
if (any(rho_dip_0 < 0.0_pReal)) extmsg = trim(extmsg)//' rho_dip_0'
if (any(prm%v_0 < 0.0_pReal)) extmsg = trim(extmsg)//' v_0'
if (any(prm%b_sl <= 0.0_pReal)) extmsg = trim(extmsg)//' b_sl'
if (any(prm%Q_s <= 0.0_pReal)) extmsg = trim(extmsg)//' Q_s'
if (any(prm%tau_Peierls < 0.0_pReal)) extmsg = trim(extmsg)//' tau_Peierls'
if (any(prm%D_a <= 0.0_pReal)) extmsg = trim(extmsg)//' D_a or b_sl'
if (any(prm%f_at <= 0.0_pReal)) extmsg = trim(extmsg)//' f_at or b_sl'
else slipActive
rho_mob_0= emptyRealArray; rho_dip_0 = emptyRealArray
allocate(prm%b_sl,prm%D_a,prm%i_sl,prm%f_at,prm%tau_Peierls, &
prm%Q_s,prm%v_0,prm%p,prm%q,prm%B,prm%h,prm%w,prm%omega, &
source = emptyRealArray)
allocate(prm%forestProjection(0,0))
allocate(prm%h_sl_sl (0,0))
endif slipActive
!--------------------------------------------------------------------------------------------------
! allocate state arrays
Nconstituents = count(material_phaseAt2 == ph)
sizeDotState = size(['rho_mob ','rho_dip ','gamma_sl']) * prm%sum_N_sl
sizeState = sizeDotState
call phase_allocateState(plasticState(ph),Nconstituents,sizeState,sizeDotState,0)
!--------------------------------------------------------------------------------------------------
! state aliases and initialization
startIndex = 1
endIndex = prm%sum_N_sl
stt%rho_mob => plasticState(ph)%state(startIndex:endIndex,:)
stt%rho_mob = spread(rho_mob_0,2,Nconstituents)
dot%rho_mob => plasticState(ph)%dotState(startIndex:endIndex,:)
plasticState(ph)%atol(startIndex:endIndex) = pl%get_asFloat('atol_rho',defaultVal=1.0_pReal)
if (any(plasticState(ph)%atol(startIndex:endIndex) < 0.0_pReal)) extmsg = trim(extmsg)//' atol_rho'
startIndex = endIndex + 1
endIndex = endIndex + prm%sum_N_sl
stt%rho_dip => plasticState(ph)%state(startIndex:endIndex,:)
stt%rho_dip = spread(rho_dip_0,2,Nconstituents)
dot%rho_dip => plasticState(ph)%dotState(startIndex:endIndex,:)
plasticState(ph)%atol(startIndex:endIndex) = pl%get_asFloat('atol_rho',defaultVal=1.0_pReal)
startIndex = endIndex + 1
endIndex = endIndex + prm%sum_N_sl
stt%gamma_sl => plasticState(ph)%state(startIndex:endIndex,:)
dot%gamma_sl => plasticState(ph)%dotState(startIndex:endIndex,:)
plasticState(ph)%atol(startIndex:endIndex) = 1.0e-2_pReal
! global alias
plasticState(ph)%slipRate => plasticState(ph)%dotState(startIndex:endIndex,:)
allocate(dst%Lambda_sl(prm%sum_N_sl,Nconstituents), source=0.0_pReal)
allocate(dst%threshold_stress(prm%sum_N_sl,Nconstituents), source=0.0_pReal)
plasticState(ph)%state0 = plasticState(ph)%state ! ToDo: this could be done centrally
end associate
!--------------------------------------------------------------------------------------------------
! exit if any parameter is out of range
if (extmsg /= '') call IO_error(211,ext_msg=trim(extmsg)//'(dislotungsten)')
enddo
end function plastic_dislotungsten_init
!--------------------------------------------------------------------------------------------------
!> @brief Calculate plastic velocity gradient and its tangent.
!--------------------------------------------------------------------------------------------------
pure module subroutine dislotungsten_LpAndItsTangent(Lp,dLp_dMp, &
Mp,T,ph,me)
real(pReal), dimension(3,3), intent(out) :: &
Lp !< plastic velocity gradient
real(pReal), dimension(3,3,3,3), intent(out) :: &
dLp_dMp !< derivative of Lp with respect to the Mandel stress
real(pReal), dimension(3,3), intent(in) :: &
Mp !< Mandel stress
real(pReal), intent(in) :: &
T !< temperature
integer, intent(in) :: &
ph, &
me
integer :: &
i,k,l,m,n
real(pReal), dimension(param(ph)%sum_N_sl) :: &
dot_gamma_pos,dot_gamma_neg, &
ddot_gamma_dtau_pos,ddot_gamma_dtau_neg
Lp = 0.0_pReal
dLp_dMp = 0.0_pReal
associate(prm => param(ph))
call kinetics(Mp,T,ph,me,dot_gamma_pos,dot_gamma_neg,ddot_gamma_dtau_pos,ddot_gamma_dtau_neg)
do i = 1, prm%sum_N_sl
Lp = Lp + (dot_gamma_pos(i)+dot_gamma_neg(i))*prm%P_sl(1:3,1:3,i)
forall (k=1:3,l=1:3,m=1:3,n=1:3) &
dLp_dMp(k,l,m,n) = dLp_dMp(k,l,m,n) &
+ ddot_gamma_dtau_pos(i) * prm%P_sl(k,l,i) * prm%nonSchmid_pos(m,n,i) &
+ ddot_gamma_dtau_neg(i) * prm%P_sl(k,l,i) * prm%nonSchmid_neg(m,n,i)
enddo
end associate
end subroutine dislotungsten_LpAndItsTangent
!--------------------------------------------------------------------------------------------------
!> @brief Calculate the rate of change of microstructure.
!--------------------------------------------------------------------------------------------------
module subroutine dislotungsten_dotState(Mp,T,ph,me)
real(pReal), dimension(3,3), intent(in) :: &
Mp !< Mandel stress
real(pReal), intent(in) :: &
T !< temperature
integer, intent(in) :: &
ph, &
me
real(pReal) :: &
VacancyDiffusion
real(pReal), dimension(param(ph)%sum_N_sl) :: &
gdot_pos, gdot_neg,&
tau_pos,&
tau_neg, &
v_cl, &
dot_rho_dip_formation, &
dot_rho_dip_climb, &
dip_distance
associate(prm => param(ph), stt => state(ph),&
dot => dotState(ph), dst => dependentState(ph))
call kinetics(Mp,T,ph,me,&
gdot_pos,gdot_neg, &
tau_pos_out = tau_pos,tau_neg_out = tau_neg)
dot%gamma_sl(:,me) = (gdot_pos+gdot_neg) ! ToDo: needs to be abs
VacancyDiffusion = prm%D_0*exp(-prm%Q_cl/(kB*T))
where(dEq0(tau_pos)) ! ToDo: use avg of pos and neg
dot_rho_dip_formation = 0.0_pReal
dot_rho_dip_climb = 0.0_pReal
else where
dip_distance = math_clip(3.0_pReal*prm%mu*prm%b_sl/(16.0_pReal*PI*abs(tau_pos)), &
prm%D_a, & ! lower limit
dst%Lambda_sl(:,me)) ! upper limit
dot_rho_dip_formation = merge(2.0_pReal*dip_distance* stt%rho_mob(:,me)*abs(dot%gamma_sl(:,me))/prm%b_sl, & ! ToDo: ignore region of spontaneous annihilation
0.0_pReal, &
prm%dipoleformation)
v_cl = (3.0_pReal*prm%mu*VacancyDiffusion*prm%f_at/(2.0_pReal*pi*kB*T)) &
* (1.0_pReal/(dip_distance+prm%D_a))
dot_rho_dip_climb = (4.0_pReal*v_cl*stt%rho_dip(:,me))/(dip_distance-prm%D_a) ! ToDo: Discuss with Franz: Stress dependency?
end where
dot%rho_mob(:,me) = abs(dot%gamma_sl(:,me))/(prm%b_sl*dst%Lambda_sl(:,me)) & ! multiplication
- dot_rho_dip_formation &
- (2.0_pReal*prm%D_a)/prm%b_sl*stt%rho_mob(:,me)*abs(dot%gamma_sl(:,me)) ! Spontaneous annihilation of 2 single edge dislocations
dot%rho_dip(:,me) = dot_rho_dip_formation &
- (2.0_pReal*prm%D_a)/prm%b_sl*stt%rho_dip(:,me)*abs(dot%gamma_sl(:,me)) & ! Spontaneous annihilation of a single edge dislocation with a dipole constituent
- dot_rho_dip_climb
end associate
end subroutine dislotungsten_dotState
!--------------------------------------------------------------------------------------------------
!> @brief Calculate derived quantities from state.
!--------------------------------------------------------------------------------------------------
module subroutine dislotungsten_dependentState(ph,me)
integer, intent(in) :: &
ph, &
me
real(pReal), dimension(param(ph)%sum_N_sl) :: &
dislocationSpacing
associate(prm => param(ph), stt => state(ph),dst => dependentState(ph))
dislocationSpacing = sqrt(matmul(prm%forestProjection,stt%rho_mob(:,me)+stt%rho_dip(:,me)))
dst%threshold_stress(:,me) = prm%mu*prm%b_sl &
* sqrt(matmul(prm%h_sl_sl,stt%rho_mob(:,me)+stt%rho_dip(:,me)))
dst%Lambda_sl(:,me) = prm%D/(1.0_pReal+prm%D*dislocationSpacing/prm%i_sl)
end associate
end subroutine dislotungsten_dependentState
!--------------------------------------------------------------------------------------------------
!> @brief Write results to HDF5 output file.
!--------------------------------------------------------------------------------------------------
module subroutine plastic_dislotungsten_results(ph,group)
integer, intent(in) :: ph
character(len=*), intent(in) :: group
integer :: o
associate(prm => param(ph), stt => state(ph), dst => dependentState(ph))
outputsLoop: do o = 1,size(prm%output)
select case(trim(prm%output(o)))
case('rho_mob')
if(prm%sum_N_sl>0) call results_writeDataset(group,stt%rho_mob,trim(prm%output(o)), &
'mobile dislocation density','1/m²')
case('rho_dip')
if(prm%sum_N_sl>0) call results_writeDataset(group,stt%rho_dip,trim(prm%output(o)), &
'dislocation dipole density''1/m²')
case('gamma_sl')
if(prm%sum_N_sl>0) call results_writeDataset(group,stt%gamma_sl,trim(prm%output(o)), &
'plastic shear','1')
case('Lambda_sl')
if(prm%sum_N_sl>0) call results_writeDataset(group,dst%Lambda_sl,trim(prm%output(o)), &
'mean free path for slip','m')
case('tau_pass')
if(prm%sum_N_sl>0) call results_writeDataset(group,dst%threshold_stress,trim(prm%output(o)), &
'threshold stress for slip','Pa')
end select
enddo outputsLoop
end associate
end subroutine plastic_dislotungsten_results
!--------------------------------------------------------------------------------------------------
!> @brief Calculate shear rates on slip systems, their derivatives with respect to resolved
! stress, and the resolved stress.
!> @details Derivatives and resolved stress are calculated only optionally.
! NOTE: Against the common convention, the result (i.e. intent(out)) variables are the last to
! have the optional arguments at the end
!--------------------------------------------------------------------------------------------------
pure subroutine kinetics(Mp,T,ph,me, &
dot_gamma_pos,dot_gamma_neg,ddot_gamma_dtau_pos,ddot_gamma_dtau_neg,tau_pos_out,tau_neg_out)
real(pReal), dimension(3,3), intent(in) :: &
Mp !< Mandel stress
real(pReal), intent(in) :: &
T !< temperature
integer, intent(in) :: &
ph, &
me
real(pReal), intent(out), dimension(param(ph)%sum_N_sl) :: &
dot_gamma_pos, &
dot_gamma_neg
real(pReal), intent(out), optional, dimension(param(ph)%sum_N_sl) :: &
ddot_gamma_dtau_pos, &
ddot_gamma_dtau_neg, &
tau_pos_out, &
tau_neg_out
real(pReal), dimension(param(ph)%sum_N_sl) :: &
StressRatio, &
StressRatio_p,StressRatio_pminus1, &
dvel, vel, &
tau_pos,tau_neg, &
t_n, t_k, dtk,dtn, &
needsGoodName ! ToDo: @Karo: any idea?
integer :: j
associate(prm => param(ph), stt => state(ph), dst => dependentState(ph))
do j = 1, prm%sum_N_sl
tau_pos(j) = math_tensordot(Mp,prm%nonSchmid_pos(1:3,1:3,j))
tau_neg(j) = math_tensordot(Mp,prm%nonSchmid_neg(1:3,1:3,j))
enddo
if (present(tau_pos_out)) tau_pos_out = tau_pos
if (present(tau_neg_out)) tau_neg_out = tau_neg
associate(BoltzmannRatio => prm%Q_s/(kB*T), &
dot_gamma_0 => stt%rho_mob(:,me)*prm%b_sl*prm%v_0, &
effectiveLength => dst%Lambda_sl(:,me) - prm%w)
significantPositiveTau: where(abs(tau_pos)-dst%threshold_stress(:,me) > tol_math_check)
StressRatio = (abs(tau_pos)-dst%threshold_stress(:,me))/prm%tau_Peierls
StressRatio_p = StressRatio** prm%p
StressRatio_pminus1 = StressRatio**(prm%p-1.0_pReal)
needsGoodName = exp(-BoltzmannRatio*(1-StressRatio_p) ** prm%q)
t_n = prm%b_sl/(needsGoodName*prm%omega*effectiveLength)
t_k = effectiveLength * prm%B /(2.0_pReal*prm%b_sl*tau_pos)
vel = prm%h/(t_n + t_k)
dot_gamma_pos = dot_gamma_0 * sign(vel,tau_pos) * 0.5_pReal
else where significantPositiveTau
dot_gamma_pos = 0.0_pReal
end where significantPositiveTau
if (present(ddot_gamma_dtau_pos)) then
significantPositiveTau2: where(abs(tau_pos)-dst%threshold_stress(:,me) > tol_math_check)
dtn = -1.0_pReal * t_n * BoltzmannRatio * prm%p * prm%q * (1.0_pReal-StressRatio_p)**(prm%q - 1.0_pReal) &
* (StressRatio)**(prm%p - 1.0_pReal) / prm%tau_Peierls
dtk = -1.0_pReal * t_k / tau_pos
dvel = -1.0_pReal * prm%h * (dtk + dtn) / (t_n + t_k)**2.0_pReal
ddot_gamma_dtau_pos = dot_gamma_0 * dvel* 0.5_pReal
else where significantPositiveTau2
ddot_gamma_dtau_pos = 0.0_pReal
end where significantPositiveTau2
endif
significantNegativeTau: where(abs(tau_neg)-dst%threshold_stress(:,me) > tol_math_check)
StressRatio = (abs(tau_neg)-dst%threshold_stress(:,me))/prm%tau_Peierls
StressRatio_p = StressRatio** prm%p
StressRatio_pminus1 = StressRatio**(prm%p-1.0_pReal)
needsGoodName = exp(-BoltzmannRatio*(1-StressRatio_p) ** prm%q)
t_n = prm%b_sl/(needsGoodName*prm%omega*effectiveLength)
t_k = effectiveLength * prm%B /(2.0_pReal*prm%b_sl*tau_pos)
vel = prm%h/(t_n + t_k)
dot_gamma_neg = dot_gamma_0 * sign(vel,tau_neg) * 0.5_pReal
else where significantNegativeTau
dot_gamma_neg = 0.0_pReal
end where significantNegativeTau
if (present(ddot_gamma_dtau_neg)) then
significantNegativeTau2: where(abs(tau_neg)-dst%threshold_stress(:,me) > tol_math_check)
dtn = -1.0_pReal * t_n * BoltzmannRatio * prm%p * prm%q * (1.0_pReal-StressRatio_p)**(prm%q - 1.0_pReal) &
* (StressRatio)**(prm%p - 1.0_pReal) / prm%tau_Peierls
dtk = -1.0_pReal * t_k / tau_neg
dvel = -1.0_pReal * prm%h * (dtk + dtn) / (t_n + t_k)**2.0_pReal
ddot_gamma_dtau_neg = dot_gamma_0 * dvel * 0.5_pReal
else where significantNegativeTau2
ddot_gamma_dtau_neg = 0.0_pReal
end where significantNegativeTau2
end if
end associate
end associate
end subroutine kinetics
end submodule dislotungsten