We present a comparative study of the ground state of the one-dimensional Hubbard model. We first use a new fermion coherent state method in the framework of Fermi liquid theory by introducing a hole operator and cons...We present a comparative study of the ground state of the one-dimensional Hubbard model. We first use a new fermion coherent state method in the framework of Fermi liquid theory by introducing a hole operator and considering the interactions of two pairs electrons and holes. We construct the ground state of the Hubbard model as ｜〉=[f＋∑^tφk1σ1hk2σ2ck3σ3hk4σ4 ∏exp（ρck1σ1 hk2σ2）]｜〉0,where φ and ρ are the coupling constants. Our results are then compared to those of varlational methods, density functional theory based on the exact solvable Bethe ansatz solutions, variational Monto-Carlo method （VMC） as well as to the exact result of the infinite system. We find satisfactory agreement between the fermion coherent state scheme and the VMC data, and provide a new picture to deal with the strongly correlated system.展开更多
文摘在Ni-Al合金粉上浸渍硝酸铜溶液,经不同温度焙烧得到Cu改性Ni-Al合金粉,采用质量分数10%NaOH溶液浸渍上述改性合金粉得Cu/Raney-Ni催化剂。采用EDX、XRD、N 2吸附-脱附、TEM和NH 3-TPD等手段表征了Ni-Al合金粉及相应Raney-Ni催化剂的元素含量、晶体结构、孔结构特征、表面形貌和表面酸碱性,并以1,4-丁烯二醇加氢制1,4-丁二醇为探针反应,考察了焙烧温度对Raney-Ni催化剂加氢性能的影响。表征分析表明,焙烧温度500℃所制备的CRT500催化剂比表面积较大,为64.96 m 2/g;弱酸中心比例较高,达81.2%。结果表明,焙烧温度升高,BED可实现完全转化,BDO选择性和收率均先升高后降低。其中,CRT500加氢性能较好,BED转化率为100.00%,BDO选择性为61.88%。进一步升高焙烧温度,催化剂RCT550和RCT600的BDO选择性和收率反而降低,这是由于高温下催化剂易发生团聚或烧结。结合催化剂表征可知,CRT500具有较好的加氢性能,这与该催化剂具有合适的Ni/Al物质的量比(3.84)、弱酸中心所占比例较大和活性组分Ni分散性好等因素有较大关联。
基金The project supported by National Natural Science Foundation of China under Grant No. 10575087 We gratefully acknowledge Dr. H. Jeshker at Freie Universitgt Berlin for his valuable discussions. Thanks are also given to the center 0f Nonlinear Science for providing the powerful sG~ 02000 Computer.
文摘We present a comparative study of the ground state of the one-dimensional Hubbard model. We first use a new fermion coherent state method in the framework of Fermi liquid theory by introducing a hole operator and considering the interactions of two pairs electrons and holes. We construct the ground state of the Hubbard model as ｜〉=[f＋∑^tφk1σ1hk2σ2ck3σ3hk4σ4 ∏exp（ρck1σ1 hk2σ2）]｜〉0,where φ and ρ are the coupling constants. Our results are then compared to those of varlational methods, density functional theory based on the exact solvable Bethe ansatz solutions, variational Monto-Carlo method （VMC） as well as to the exact result of the infinite system. We find satisfactory agreement between the fermion coherent state scheme and the VMC data, and provide a new picture to deal with the strongly correlated system.
