n
u
m
b
e
r
o
f
a
t
o
m
s
3
0
w
a
v
e
v
e
c
t
o
r
(
k
)
0
.
1
a
m
p
l
i
t
u
d
e
(
ϵ
)
0
.
2
t
0
.