Energy resolution and discretization artifacts in the numerical renormalization group

Adaptive logarithmic discretization for numerical renormalization group methods

The problem of the logarithmic discretization of an arbitrary positive function (such as the density of states) is studied in general terms. Logarithmic discretization has arbitrary high resolution around some chosen point (such as Fermi level) and it finds application, for example, in the numerical renormalization group (NRG) approach to quantum impurity problems (Kondo model), where the conti...

A NUMERICAL RENORMALIZATION GROUP APPROACH FOR AN ELECTRON-PHONON INTERACTION

A finite chain calculation in terms of Hubbard X-operators is explored by setting up a vibronic Harniltonian. The model conveniently transformed into a form so that in the case of strong coupling a numerical renormalization group approach is applicable. To test the technique, a one particle Green function is calculated for the model Harniltonian

supply and demand security of energy in central asia and the caucasus

امنیت انرژی به معنی عرضه مداوم و پایدار همراه با قیمت های معقول در حامل های انرژی، که تهدیدات امنیتی، سیاسی، اقتصادی، محیط زیستی و روانی را کاهش دهد. امروزه نفت و گاز تنها، کالای تجاری نیست بلکه بعنوان ابزار سیاسی مورد استفاده قرار می گیرد.اختلاف میان روسیه و اکراین بر سر انرژی در ژانویه 2006، تهدیدی برای امنیت انرژی اروپا ایجاد کرد. در این تحقیق ما تلاش کردیم که نقش انرژی آسیای میانه و قفقاز ر...

1 Wilson’s Numerical Renormalization Group

The idea of the numerical renormalization group (NRG) for a quantum-mechanical system with Hamiltonian H is to obtain the many-body eigen-states and eigenvalues on all energy scales ω 1 > ω 2 >. .. in a sequence of steps, with each step corresponding to a distinct energy or length scale [1]. This is achieved by a formal procedure of tracing out high energy states to (RG) transformation R relate...

12 The Numerical Renormalization Group Ralf