First principles study of the Fermi surface topology of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>CeCu</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mi>Si</mml:mi> <mml:mn>2</mml:mn> </mml:msub>

Since the discovery of heavy-fermion superconductivity in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi>CeCu</a:mi> <a:mn>2</a:mn> </a:msub> <a:msub> <a:mi>Si</a:mi> <a:mn>2</a:mn> </a:msub> </a:mrow> </a:math> , the material has attracted great interest, particularly with regard to the nature of the superconducting pairing and its mechanism. Consequently, it is essential to better understand the electronic Fermi surface topology and its role in strong antiferromagnetic fluctuations. The standard density functional theory method is insufficient to model the interplay of strong on-site Coulomb repulsion in localized <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:mn>4</b:mn> <b:mi>f</b:mi> </b:mrow> </b:math> electrons and their hybridization with itinerant ligand-orbital electrons. We have performed electronic ground-state calculations on <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msub> <c:mi>CeCu</c:mi> <c:mn>2</c:mn> </c:msub> <c:msub> <c:mi>Si</c:mi> <c:mn>2</c:mn> </c:msub> </c:mrow> </c:math> using the Gutzwiller wave function approximation. The Gutzwiller approximation captures the quasiparticle band renormalization from the strong on-site Coulomb repulsion. We have performed an analysis of this effect on the electronic structure and the Fermi surface topology by varying the interaction strength and taking into account the crystal-field splitting. Using the de Haas-van Alphen effect, the extremal Fermi surface cross-sectional areas were calculated to quantify the effects of quasiparticle mass renormalization on the Fermi surface. Our results confirm the presence of two Fermi surface sheets corresponding to the heavy ( <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mn>488</d:mn> <d:msub> <d:mi mathvariant="italic">m</d:mi> <d:mi>e</d:mi> </d:msub> </d:mrow> </d:math> ) and light ( <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mrow> <f:mn>4.35</f:mn> <f:msub> <f:mi mathvariant="italic">m</f:mi> <f:mi>e</f:mi> </f:msub> </f:mrow> </f:math> ) quasiparticles when the crystal-field splitting is accounted for on equal footing with the electronic correlations. This method gives the best agreement with experimental measurements as well as the renormalized band method.