Electronic Journal of Differential Equations, Vol. 2023 (2023), No. 75, pp. 1-20. Title: Concentration of nodal solutions for semiclassical quadratic Choquard equations Authors: Lu Yang (Yunnan Univ., Kunming, China) Xiangqing Liu (Yunnan Normal Univ., Kunming, China) Jianwen Zhou (Yunnan Univ., Kunming, China) Abstract: In this article concerns the semiclassical Choquard equation $-\varepsilon^2 \Delta u +V(x)u = \varepsilon^{-2}( \frac{1}{|\cdot|}* u^2)u$ for $x \in \mathbb{R}^3$ and small $\varepsilon$. We establish the existence of a sequence of localized nodal solutions concentrating near a given local minimum point of the potential function $V$, by means of the perturbation method and the method of invariant sets of descending flow. Submitted May 18, 2023. Published October 30, 2023. Math Subject Classifications: 35B05, 35B45. Key Words: Choquard equation; sign-changing solution; perturbation method; Fredholm operator; nodal solution.