各位版主、大神:
你们好。我想问几个关于LAMMPS建模的基本问题。我知道可能有点简单,但我真的是认真查看过Manual中相关的命令说明之后,仍有一些疑问。我自己想了很久,也问过很多人,但是还是没有解决。
命令来自一个很基础的LAMMPS例子,该例子的全部命令如下:
# Find minimum energy fcc configuration
# Mark Tschopp,
# ---------- Initialize Simulation ---------------------
clear
units metal
dimension 3
boundary p p p
atom_style atomic
atom_modify map array
# ---------- Create Atoms ---------------------
latticefcc 4
region box block 0 1 0 1 0 1 units lattice
create_box 1 box
lattice fcc 4 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1
create_atoms 1 box
replicate 1 1 1
# ---------- Define Interatomic Potential ---------------------
pair_style eam/alloy
pair_coeff * * Al99.eam.alloy Al
neighbor 2.0 bin
neigh_modify delay 10 check yes
# ---------- Define Settings ---------------------
compute eng all pe/atom
compute eatoms all reduce sum c_eng
# ---------- Run Minimization ---------------------
reset_timestep 0
fix 1 all box/relax iso 0.0 vmax 0.001
thermo 10
thermo_style custom step pe lx ly lz press pxx pyy pzz c_eatoms
min_style cg
minimize 1e-25 1e-25 5000 10000
variable natoms equal "count(all)"
variable teng equal "c_eatoms"
variable length equal "lx"
variable ecoh equal "v_teng/v_natoms"
print "Total energy (eV) = ${teng};"
print "Number of atoms = ${natoms};"
print "Lattice constant (Angstoms) = ${length};"
print "Cohesive energy (eV) = ${ecoh};"
print "All done!"
我的问题是:
(1)lattice fcc 4 和 lattice fcc 4 orient x 100 orient y 0 1 0 orient z 0 0 1这两句有什么区别?效果不是一样的么?为什么在lattice fcc 4建立格子之后,还要有lattice fcc 4 orient x 100 orient y 0 1 0 orient z 0 0 1这句?意义何在?
(2)replicate 1 1 1这句不相当于没有复制么?为什么要写这条命令呢?意义何在?
(3)如果我只想建模,不进行任何计算,然后想在LAMMPS中导出该模型,最后在VMD中查看该模型。那么在整个代码的最后一行需要添加一个怎样的dump语句?(我查过手册中的dump语句,也试过很多次自己写,但是都不对。)
跪求各路大神帮助。小弟在此谢过!