24小时热门版块排行榜

返回列表

当前主题已经存档。

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

linxi1454

银虫 (正式写手)

应助: 0 (幼儿园)
金币: 245
散金: 1814
红花: 3
帖子: 503
在线: 43.1小时
虫号: 443673
注册: 2007-10-27
专业: 半导体物理

[交流] 【求助】请教两种基组的区别

请教两种基组的区别
分别是HF/6-31G* 和 B3LYP/cc-pVTZ

感谢解惑

回复此楼

» 猜你喜欢

调剂招生已经有0人回复
调剂招生已经有0人回复
物理化学论文润色/翻译怎么收费? 已经有57人回复
调剂招生已经有0人回复
调剂招生已经有1人回复
实际气体内压强的微观机制或将改写--------从一个基本的力学佯谬说起已经有2人回复
调剂招生已经有0人回复
调剂招生已经有0人回复
调剂招生已经有5人回复
招收0703开头的学硕调剂生线上复试已经有5人回复
湖北文理学院材料与化工专硕还有调剂名额，欢迎大家推荐考生！已经有1人回复

1楼 2009-03-04 00:09:13

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

erylingjet

铁杆木虫 (著名写手)

应助: 0 (幼儿园)
贵宾: 5.372
金币: 9933.4
散金: 752
红花: 2
帖子: 2248
在线: 241.5小时
虫号: 415302
注册: 2007-06-28
性别: GG
专业: 计算化学

★ ★ ★ ★
lei0736(金币+4,VIP+0):谢谢 3-4 10:33

The most common type of ab-initio calculation is called Hartree-Fock calculation(abbreviated HF), in which the primary approximation is called the mean field approximation. This means that the Coulombic electron-electron repulsion is not explicitly taken into account, however, its average effect is included in the calculation. This is a variational calculation, which implies that the approximate energies calculated are all equal to or greater than the exact energy. The accuracy of the calculation depends on the size of the basis set used, however because of the mean field approximation, the
energies from HF calculations are always greater than the exact energy and tend, with increasing basis size, to a limiting value called the Hartree-Fock limit.

An alternative ab-initio method is Density Functional Theory (DFT), in which the
total energy is expressed in terms of the total electron density, rather than the
wavefunction. This type of calculation leads to an approximate effective or model
Hamiltonian and to an approximate expression for the total electron density. Often the
electron density approximations are made using some empirical corrections. Such DFT
approaches are related to semi-empirical methods