Studi simulasi pengaruh arah polarisasi, jarak antar partikel, dan ukuran partikel terhadap sifat localized surface plasmon resonance nanopartikel perak dengan model bola ganda menggunakan metode elemen batas = Simulation study of the polarization, distance, and diameter of particles effect to localized surface plasmon resonance Properties of silver nanoparticles with double spheres models using boundary element method