[Author] Mishulovich, A. A. [Title] Homogenization of a multidimensional periodic elliptic operator at the edge of a spectral gap: Operator estimates in the energy norm [AMS Subj-class] 35B27 Homogenization; partial differential equations in media with periodic structure [Keywords] periodic differential operators, spectral bands, homogenization, effective operator, corrector, operator error estimates [Abstract] We consider an elliptic differential operator $\mathcal{A}_{\varepsilon} = - \operatorname{div}\widetilde{g}(\boldsymbol{x}/\varepsilon) \nabla + \varepsilon^{-2} V(\boldsymbol{x}/\varepsilon), $ \varepsilon > 0$, with periodic coefficients acting in $L_2(\mathbb{R}^{d})$. For small $ \varepsilon$, we study the behavior of the resolvent of the operator $ \mathcal{A}_{\varepsilon} $ in a regular point close to the edge of a spectral gap. We obtain an approximation of this resolvent in the “energy” norm with error $O(\varepsilon)$. [Comments] Russian, 49 pp. [Contact e-mail] st062829@student.spbu.ru