A NEW EMBEDDED-ATOM METHOD INTERATOMIC POTENTIAL FOR TUNGSTEN-HYDROGEN SYSTEM

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Dustin Hensley
5 years ago
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Shu 1, Guang-Hong Lu 1* 1 School of Physics and Nuclear

People s Republic of China 2 Department of Nuclear

1 A NEW EMBEDDED-ATOM METHOD INTERATOMIC POTENTIAL FOR TUNGSTEN-HYDROGEN SYSTEM Li-Fang Wang 1, Fei Gao 2, Xiao-Lin Shu 1, Guang-Hong Lu 1* 1 School of Physics and Nuclear Energy Engineering, Beihang University, Beijing , People s Republic of China 2 Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, MI, United States

2 OUTLINE Background: An investigation of interatomic potentials for W-H system Potential formalism and parametrization Results and discussion Basic Point defects Interaction of H atoms with other defects (H atoms, SIAs, vacancies) in BCC W Thermal properties: H diffusion Conclusions

3 OUTLINE Background: An investigation of interatomic potentials for W-H system Potential formalism and parametrization Results and discussion Basic Point defects Interaction of H atoms with other defects (H atoms, SIAs, vacancies) in BCC W Thermal properties: H diffusion Conclusions

4 Background An investigation of interatomic potentials for W-H system BOP-type potentials: W-C-H_Juslin (2005) [Juslin N, Erhart P, Träskelin P, et al. Analytical interatomic potential for modeling nonequilibrium processes in the W C H system[j]. Journal of Applied Physics, 2005, 98(12): ] W-H-He_Li (2012) [Li X C, Shu X, Liu Y N, et al. Analytical W He and H He interatomic potentials for a W H He system[j]. Journal of Nuclear Materials, 2012, 426(1): ] EAM-type potentials: W-H-He_Bonny (2014) [Bonny G, Grigorev P, Terentyev D. On the binding of nanometric hydrogen helium clusters in tungsten[j]. Journal of Physics: Condensed Matter, 2014, 26(48): ] A COMPARISON

5 Background An investigation of interatomic potentials for W-H system Basic Properties First Principles Too slow because of the long cutoff POT_Juslin POT_Li POT_Bonny1 POT_Bonny2,,, tet-oct) Position (H in V) 0.10 off OIS 0.08 off OIS 0.19 off OIS Center of vacancy 0.35 off OIS NAN NAN

6 OUTLINE Background: An investigation of interatomic potentials for W-H system Potential formalism and parametrization Results and discussion Basic Point defects Interaction of H atoms with other defects (H atoms, SIAs, vacancies) in BCC W Thermal properties: H diffusion Conclusions

7 Potential formalism and parametrization W-W interaction: two choices A. EAM_WW_Marinica B. EAM_WW_Acland&Juslin ( x) n 3 ai ( i x) ( i x) i1 n 3 ( x) ai ( i x) ( i x) i1 F F 2 ( ) 1 2 F x a x a x W-W interaction evaluation FP EAM2_Marinica EAM_ModAcland VZBL 10, rij ri V( r) ar ar ar ar ar a, r r r V ATPOT V r Bb r r ij 5 ij 4 ij 3 ij 2 ij 1 ij 0 1 ij 2 3 ATPOT ( ij ) ( 0 ij ) exp( ij ) ( r r) ( c cr cr ), r r ( rij) 0, rij r 2 ( ri rd), ri rd 0, ri rd F( ) A i 2 2 ij c 0 1 ij 2 ij ij c [Marinica M C, Ventelon L, Gilbert M R, et al. Interatomic potentials for modelling radiation defects and dislocations in tungsten[j]. Journal of Physics: Condensed Matter, 2013, 25(39): ] [Juslin N, Wirth B D. Interatomic potentials for simulation of He bubble formation in W[J]. Journal of Nuclear Materials, 2013, 432(1): ]

8 Potential formalism and parametrization W-H interaction H-H interaction 2 k ( r k ) - k ( r k ) WH k1 e e fc rij 2 ij 3 2 ij 3 [ 2 ] ( ) kr 5 i 2kr 5 i ( 2 ) ( ) 6 9 H 4 i c i ( r ), r r ( r A) H 0 0 H mod 0 H ( r), r r0 F ( ) k k 2 8 H i 6 i 7 i k9 f ( r ) e c kr e e f r i 1 r r i Hc 5 3 i k i ( r ) s( r )[ E ( r ) 2 F ( )] [1 s( r )] * HH ij ij mol ij H H ij HH 2 k ( r k ) - k ( r k ) HH kh 1 e e fc rij H 2 ij H 3 H 2 ij H 3 [ 2 ] ( ) Sr ( ) 0.5{1 tanh[15( r0.9)]} ij E r a e mol ( ij ) 4.74(1 ) ( r ij r0 ) a, r nm, r0 ij a identical transformation = S * H H H F ( ) F ( / S ) * H H H [Angelo J E, Moody N R, Baskes M I. Trapping of hydrogen to lattice defects in nickel[j]. Modelling and Simulation in Materials Science and Engineering, 1995, 3(3): 289.] [Baskes M I, Sha X, Angelo J E, et al. Trapping of hydrogen to lattice defects in nickel[j]. Modelling and Simulation in Materials Science and Engineering, 1997, 5(6): 651.].

Potential formalism and parametrization Database properties,,,

74 properties reference 0.74-2.95-9.69-0.47-0.11-0.04 0.01 0.

9 Potential formalism and parametrization Database properties,,, tet-oct) Position (H in V) Position1 (H in V) Position2 (H in V) Potential Profile reference off OIS off OIS 0.90 off OIS properties reference Fitting code MATLAB Nonlinear least-squares method (nonlinear data-fitting)

10 OUTLINE Background: An investigation of interatomic potentials for W-H system Potential formalism and parametrization Results and discussion Basic Point defects Interaction of H atoms with other defects (H atoms, SIAs, vacancies) in BCC W Thermal properties: H diffusion Conclusions

11 Results and Discussion H point defects Basic Properties First Principles POT_present POT_Juslin POT_Li POT_Bonny1 POT_Bonny2,,, tet-oct) Position (H in V) 0.10 off OIS 0.12 off OIS 0.08 off OIS 0.19 off OIS Center of vacancy 0.35 off OIS NAN NAN

12 Results and Discussion Interaction between H atoms in bcc W Binding energy of two H atoms in different TIS of BCC W H G(9) (10) (4) A(1) E(6) D(5) F(8) C(3) (7) First H B(2)

Results and Discussion Interaction between H atoms and SIAs in bcc W Model: System with single [111] SIA 1~10 H atoms are added around the SIA randomly and then the

13 Results and Discussion Interaction between H atoms and SIAs in bcc W Model: System with single [111] SIA 1~10 H atoms are added around the SIA randomly and then the system is energetically minimized Repeating above process for times The most stable configuration is chosen to calculate the binding energy of H atoms to SIA.

14 Results and Discussion Interaction between H atoms and SIAs in bcc W [111] SIA of BCC W The [111] SIA structure predicted by Pot_Juslin is unstable Configuration of the H atoms binding to SIA by POT_Present

energetically minimized Repeating above process for 2000 times The most stable configuration is chosen to

15 Results and Discussion Interaction between H atoms and vacancies in bcc W Interaction between H atoms and single vacancy in BCC W 1~10 H atoms are added in the vacancy randomly and then the system is energetically minimized Repeating above process for 2000 times The most stable configuration is chosen to calculate the binding energy of H atoms to the single vacancy. Configuration Consistent with FP results.[ohawa,prb]

16 Results and Discussion Interaction between H atoms and vacancies in bcc W Interaction between H atoms and vacancy cluster in BCC W. Hydrogen-vacancy cluster Size: Number of vacancies: m=2~10 Binding energy of vacancy cluster (Binding energies of vacancy clusters are tested.) Number of H atoms: n=1~10*m (Randomly placed in the vacancy clusters repeatedly until the most stable configuration is appeared) Pot_Marinica

17 Results and Discussion Interaction between H atoms and vacancies in bcc W Interaction between H atoms and vacancy cluster in BCC W. (n/m) (m/n)

18 Results and Discussion Thermal diffusion of H atoms in bcc W 1000~3000K, 0.3% H atoms diffusion in bcc W Arrhenius fit of diffusion data / Experiment Pot_Present Pot_Juslin Pot_Bonny Pot_Bonny

19 OUTLINE Background: An investigation of interatomic potentials for W-H system Potential formalism and parametrization Results and discussion Basic Point defects Interaction of H atoms with other defects (H atoms, SIAs, vacancies) in BCC W Thermal properties: H diffusion Conclusions

20 Conclusions A new embedded-atom method (EAM) interatomic potential for tungsten-hydrogen system is developed ; The new W-H potential is thoroughly assessed compared with first principles calculations and other interatomic potential results; Basic point defect properties of W-H system, interaction between H atoms and other defects of bcc W, and thermal diffusion of H in W are all derived, and the new EAM potential perform reliable calculations compared with first-principles prediction and other interatomic potentials results.

21 The End Thank you for your attention.

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