1、Project#4 表面与界面能表面与界面能 铜的表面能铜的表面能 当物体形成表面时,表面上的原子键发生断裂,接近表面的几层原子不再如之前处于平衡状态,从而导致能量的升高,升高的温度便是物体的表面能。利用 LAMMPS 做出 20*20*40 fcc 的盒子,删去边缘的原子制造出一段真空层;算出此时体系的总能量0E,然后从中间把盒子切成两半并移至足够远的距离,此时的体系总能量为Efinal,从而表面能:02finalsurfaceEEA=A为表面的面积(100)面与面与(111)面面 如下是输入文件 in.surface_Cu_100#LAMMPS Cu _Surface_100 units
2、metal boundary p p p atom_style atomic lattice fcc 3.61 region box block 0 20 0 20 0 40 create_box 1 box create_atoms 1 box timestep 0.005 thermo 5 pair_style eam/alloy pair_coeff *jin_copper_lammps.setfl Cu region boundary1 block INF INF INF INF 29.9 INF region boundary2 block INF INF INF INF INF 9
3、.9 group boundary1 region boundary1 group boundary2 region boundary2 group boundary union boundary1 boundary2 delete_atoms group boundary neighbor 0.6 bin neigh_modify every 5 delay 0 check yes compute 3 all pe/atom compute 4 all ke/atom compute 5 all coord/atom 3.0 dump 1 all custom 100 dump.atom i
4、d xs ys zs c_3 c_4 c_5 dump_modify 1 format%d%16.9g%16.9g%16.9g%16.9g%16.9g%g min_style sd minimize 1.0e-30 1.0e-15 1000 10000 variable E equal pe print -E=$E-run 0 region down block INF INF INF INF INF 19.94 region up block INF INF INF INF 19.95 INF group up region up group down region down displac
5、e_box all z delta 0 40 units lattice remap none displace_atoms up move 0 0 40 units lattice minimize 1.0e-30 1.0e-20 10000 100000 print -SURFACE-E=$E-Plane(100)(111)Surface energy(2/mJm)1330 1228 Plane(111)Plane(100)镁的镁的 hcp/fcc 界面能界面能 计算镁的 hcp/fcc 界面能比较有趣。正如我们所知,镁是 hcp 结构的金属,它是按ABABABABAB 所排列的;当我们进
6、行一系列移动之后得到 ABABCABCAB,从而产生镁的 hcp/fcc 界面。如下是输入文件 in.hcp_fcc_vac#LAMMPS hcp_fcc_Mg units metal boundary p p p atom_style atomic lattice custom 4.5198 a1 1.224744871391589049 0 0 a2 0 0.7071067811865475244 0 a3 0 0 1.1476 basis 0.0 0.0 0.0 basis 0.5 0.5 0.0 basis 0.33333333333333333333 0.0 0.5 basis 0.
7、83333333333333333333 0.5 0.5 region box block 0 6 0 6 0 36 create_box 1 box create_atoms 1 box pair_style eam/alloy pair_coeff *mg.eam.alloy Mg neighbor 0.8 bin neigh_modify every 5 delay 0 check yes thermo 10 variable N equal atoms variable E equal pe region boundary1 block INF INF INF INF 26.9 INF
8、 region boundary2 block INF INF INF INF INF 8.9 group boundary1 region boundary1 group boundary2 region boundary2 group boundary union boundary1 boundary2 delete_atoms group boundary label dj variable x index 17.9 18.9 19.9 20.9 21.9 22.9 23.9 24.9 25.9 region up_$x block INF INF INF INF$x INF group
9、 up_$x region up_$x displace_atoms up_$x move-0.3333333333333333333333333333333333333333333333333333333 0 0 units lattice next x jump in.hcp_fcc_vac dj timestep 0.01 region part block INF INF INF INF 12 24 group part region part compute 3 all pe/atom compute 4 all ke/atom compute 5 all coord/atom 3.
10、0 dump 1 part custom 100 dump.atom id xs ys zs c_3 c_4 c_5 dump_modify 1 format%d%16.9g%16.9g%16.9g%16.9g%16.9g%g min_style sd minimize 1.0e-30 1.0e-15 10000 100000 shell mkdir dump_fcc_hcp shell mv dump.atom dump_fcc_hcp/dump.atom print -fcc_hcp-N=$N E=$E-delete_atoms group all lattice none lattice
11、 custom 4.5198 a1 1.224744871391589049 0 0 a2 0 0.7071067811865475244 0 a3 0 0 1.1476 basis 0.0 0.0 0.0 basis 0.5 0.5 0.0 basis 0.33333333333333333333 0.0 0.5 basis 0.8333333333333333333333333333333333333333333333333333 0.5 0.5 create_atoms 1 box group boundary1 region boundary1 group boundary2 regi
12、on boundary2 group boundary union boundary1 boundary2 delete_atoms group boundary undump 1 dump 1 all custom 100 dump_hcp.atom id xs ys zs c_3 c_4 c_5 dump_modify 1 format%d%16.9g%16.9g%16.9g%16.9g%16.9g%g min_style sd minimize 1.0e-30 1.0e-15 10000 10000 print -hcp-N=$N E=$E-shell mkdir dump_hcp sh
13、ell mv dump_hcp.atom dump_hcp/dump.atom delete_atoms group all lattice none lattice custom 4.5198 a1 1.224744871391589049 0 0 a2 0 0.7071067811865475244 0 a3 0 0 1.1476 basis 0.0 0.0 0.0 basis 0.5 0.5 0.0 basis 0.33333333333333333333 0.0 0.5 basis 0.83333333333333333333 0.5 0.5 create_atoms 1 box gr
14、oup boundary1 region boundary1 group boundary2 region boundary2 group boundary union boundary1 boundary2 delete_atoms group boundary label ddj variable y index 9.9 10.9 11.9 12.9 13.9 14.9 15.9 16.9 17.9 18.9 19.9 20.9 21.9 22.9 23.9 24.9 25.9 region up_fcc_$y block INF INF INF INF$y INF group up_fc
15、c_$y region up_fcc_$y displace_atoms up_fcc_$y move-0.333333333333333333333333333333333333333333333333333333333 0 0 units lattice next y jump in.hcp_fcc_vac ddj undump 1 dump 1 all custom 1000 dump_fc.atom id xs ys zs c_3 c_4 c_5 dump_modify 1 format%d%16.9g%16.9g%16.9g%16.9g%16.9g%g min_style sd minimize 1.0e-30 1.0e-15 10000 100000 shell mkdir dump_fcc shell mv dump_fcc.atom dump_fcc/dump.atom print -fcc-N=$N E=$E-根据公式:thcpfcc1E(EE)22A+=+=可以得到:227.058(mJ/m)=,这与之前所得到结果比较吻合。
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