Lcao

Found 10 free book(s)

基礎量子化学 - 福井大学

acbio2.acbio.u-fukui.ac.jp

根拠14・4二原子分子のlcao-moを変分法を用いて決める二原子分子abの分子オービタルとしてlcao-mo を用いる． ψ=caa＋cbb ここで，aおよびbは，それぞれ原子aおよびbのaoである．このlcao-moを試行関数としてエネルギーeが最小となるように係数

Cola

Handout 8 Linear Combination of Atomic Orbitals (LCAO)

courses.cit.cornell.edu

Linear Combination of Atomic Orbitals (LCAO) Now consider a Hydrogen molecule made up of two covalently bonded Hydrogen atoms sitting at a distance of 2d from each other, as shown: Hamiltonian for an electron is: V r dx V r dx m H ˆ ˆ 2 ˆ 2 2 The basic idea behind LCAO approach is to construct a trial variational solution in

Linear, Combination, Atomic, Orbitals, Cola, Linear combination of atomic orbitals

Optimisation of Basis Sets and Pseudopotentials - CP2K

www.cp2k.org

LCAO 3 LCAO: Linear Combination of Atomic Orbitals molecular orbital (MO) atomic orbital (basis function) MO coefficient (unknown) Jensen, Introduction to Computational Chemistry, Wiley (2007) 4 Gaussian type orbitals (GTOs) sum of l x, l y, l z determines type of orbital:

Sets, Basis, Cola, Optimisation, Pseudopotentials, Optimisation of basis sets and pseudopotentials

Simple Molecular Orbital Theory - University of California ...

www.chem.uci.edu

LCAO MO Energy Diagram for H2 Energy H-H ∆E1 ∆E2 • ∆E2> ∆E1, so the antibonding orbital is always more anti-bonding than the bonding orbital is bonding H2molecule: two 1s atomic orbitals combine to make one bonding and one antibonding molecular orbital. Ha Hb

Cola

Simple Molecular Orbitals - Sigma and Pi Bonds in ... - CPP

www.cpp.edu

LCAO = linear combination of atomic orbitals node = zero electron density because of opposite phases ∆E = bond energy There is a big energy advantage for a hydrogen molecule over two hydrogen atoms. Sigma (σ) bonding molecular orbital - Shared electron density is directly between the bonding atoms, along the bonding axis.

Cola

5.4 紧束缚模型 (tight-binding model) - USTC

staff.ustc.edu.cn

- Linear combination of atomic orbitals (LCAO) 首先忽略电子之间相互作用，其次采用单电子近似 2 H i m V Ai V Bi] i i i 2 [2 则猜测波函数为两个原子的线性组合： i C i A (r i ) i B (r i) 若两个波函数相等，可以解出 1 C ( A B) 2 2() * * C H aa H ab dr

Binding, Cola

AN INTRODUCTION TO QUANTUM CHEMISTRY

www.msg.chem.iastate.edu

LCAO APPROXIMATION • Increase # AO’s - approach exact HF • Requires complete (infinite) basis χ µ • Computational effort increases ~ N4 – Double # AO’s, effort goes up by factor of 16! – Need to balance accuracy with CPU time, memory ψ ι = ∑ µ χµ Cµ i

Cola

MO Diagrams for Diatomic Molecules

www.chem.uci.edu

• LCAO-MO Theory is a simple method for predicting the approximate electronic structure of molecules. • Atomic orbitals must have the proper symmetry and energy to interact and form molecular orbitals. • Photoelectron spectroscopy provides useful information on the energies of …

Cola