The present paper is devoted to the study of the following double-phase equation $$\begin{aligned} -\text {div}(|\nabla u|^{p-2}\nabla u+\mu _{\varepsilon }(x)|\nabla u|^{q-2}\nabla u)+V_{\varepsilon }(x)(|u|^{p-2}u+\mu _{\varepsilon }(x)|u|^{q-2}u)=f(u)\quad \text{ in }\quad \mathbb {R}^{N}, \end{aligned}$$
-
div
(
|
∇
u
|
p
-
2
∇
u
+
μ
ε
(
x
)
|
∇
u
|
q
-
2
∇
u
)
+
V
ε
(
x
)
(
|
u
|
p
-
2
u
+
μ
ε
(
x
)
|
u
|
q
-
2
u
)
=
f
(
u
)
in
R
N
,
where $$N\ge 2$$
N
≥
2
, $$1<p<q<N$$
1
<
p
<
q
<
N
, $$q<p^{*}$$
q
<
p
∗
with $$p^{*}=\frac{Np}{N-p}$$
p
∗
=
Np
N
-
p
, $$\mu :\mathbb {R}^{N}\rightarrow \mathbb {R}$$
μ
:
R
N
→
R
is a continuous non-negative function, $$\mu _{\varepsilon }(x)=\mu (\varepsilon x)$$
μ
ε
(
x
)
=
μ
(
ε
x
)
, $$V:\mathbb {R}^{N}\rightarrow \mathbb {R}$$
V
:
R
N
→
R
is a positive potential satisfying a local minimum condition, $$V_{{{\,\mathrm{\varepsilon }\,}}}(x)=V({{\,\mathrm{\varepsilon }\,}}x)$$
V
ε
(
x
)
=
V
(
ε
x
)
, and the nonlinearity $$f:\mathbb {R}\rightarrow \mathbb {R}$$
f
:
R
→
R
is a continuous function with subcritical growth. Under natural assumptions on $$\mu $$
μ
, V and f, by using penalization methods and Lusternik–Schnirelmann theory we first establish the multiplicity of solutions, and then, we obtain concentration properties of solutions.