نتایج جستجو برای: تقریب lda u
تعداد نتایج: 174628 فیلتر نتایج به سال:
We present a new approach to the evaluation of the on-site repulsion energy U for use in the LDA+U method of Anisimov and collaborators. Our objectives are to make the method more firmly based, to concentrate primarily on ground state properties rather than spectra, and to test the method in cases where only modest changes in orbital occupations are expected, as well as for highly correlated ma...
Standard LDA model suffers the problem that the topic assignment of each word is independent and word correlation hence is neglected. To address this problem, in this paper, we propose a model called Word Related Latent Dirichlet Allocation (WR-LDA) by incorporating word correlation into LDA topic models. This leads to new capabilities that standard LDA model does not have such as estimating in...
Linear Discriminant Analysis (LDA) is a popular feature extraction technique for face image recognition and retrieval. However, It often suffers from the small sample size problem when dealing with the high dimensional face data. Two-step LDA (PCA+LDA) [1–3] is a class of conventional approaches to address this problem. But in many cases, these LDA classifiers are overfitted to the training set...
In face recognition, LDA often encounters the so-called small sample size (SSS) problem, also known as curse of dimensionality. This problem occurs when the dimensionality of the data is quite large in comparison to the number of available training images. One of the approaches for handling this situation is the subspace LDA. It is a two-stage framework: it first uses PCA-based method for dimen...
Recently a kind of matrix-based discriminant feature extraction approach called 2DLDA have been drawn much attention by researchers. 2DLDA can avoid the singularity problem and has low computational costs and has been experimentally reported that 2DLDA outperforms traditional LDA. In this paper, we compare 2DLDA with LDA in view of the discriminant power and find that 2DLDA as a kind of special...
OBJECTIVES The objectives of this study are to examine the efficacy and safety of low-dose aspirin (LDA) vs LDA plus low-intensity warfarin (LDA + W) in the primary thrombosis prevention of aPL-positive patients with SLE and/or obstetric morbidity and the role of clinical and serological markers in the development of thrombosis. METHODS In this 5-year prospective, randomized, open, controlled...
بررسی دستگاه های الکترونی همبسته قوی به دلیل خواص غـیر قابل پیش بینی و کاربرد های منحصر به فرد آنها از اهمیت ویژه ای برخوردار است. این ترکیبات به طور عمده شامل عناصری می باشند که تراز d یا f آنها در حال پر شدن است. لذا جستجو برای رهیافت هایی که بتواند خواص ساختاری و الکترونی این دستگاه ها را مورد بررسی قرار دهد به طور ویژه ای مورد توجه قرار گرفته است. از جمله این رهیافت ها می توان به نظریه تابع...
The density functional based calculations of the electronic structure of YMnO3 are performed for selected spin configurations and from the differences of the total energies the exchange integrals are determined. To improve the description of strongly correlated 3d electrons of Mn the LDA + U method is employed. The strongest exchange interaction is found between the nearest neighbor Mn spins, t...
یکی از مهم ترین مسائل و چالش های جهان مدرن، یافتن منابع جدید انرژی می باشد. امروزه، مواد ترموالکتریک با تبدیل مستقیم گرما به الکتریسیته به عنوان یک منبع انرژی تلقی می شوند که می توانند در کاهش گرمای زمین نیز موثر واقع شوند. یکی از نویدبخش ترین کاربردهای ترموالکتریک در صنعت خودروسازی است. به طوریکه شرکت ژنرال موتور بیان داشته است که کاهش تنها 10 درصدی در مصرف سوخت تنها در خودروهای ساخت این شرکت،...
We present results of GGA+U calculations for the “d magnet” RbO2, where magnetic properties are due to partially filled oxygen p orbitals. We show that on-site interactions on the oxygen sites lead to a strong tendency towards the formation of an orbitally polarized insulating state, in contrast to the half-metallic behavior predicted for this class of compounds within pure LDA/GGA. The obtaine...
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