From 9bfab327a2cbd6faee0af35de526b50b145eb942 Mon Sep 17 00:00:00 2001
From: Donjan Rodic <donjan@dyx.ch>
Date: Tue, 26 Apr 2016 10:13:50 +0200
Subject: [PATCH] added to ex08 solution: drawbacks
---
exercises/ex08_solution/hartree-fock.ipynb | 24 +++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/exercises/ex08_solution/hartree-fock.ipynb b/exercises/ex08_solution/hartree-fock.ipynb
index c538bd0..6edac45 100644
--- a/exercises/ex08_solution/hartree-fock.ipynb
+++ b/exercises/ex08_solution/hartree-fock.ipynb
@@ -352,7 +352,29 @@
"cell_type": "markdown",
"metadata": {},
"source": [
- "Don't forget to add 1 to the resulting energy: during derivation, the repulsion of the H cores (which is normalised to $1$ Hartree) has been left out."
+ "Don't forget to add 1 to the resulting energy: during derivation, the repulsion of the H cores ( $\\frac{1}{|R_A-R_B|}=1$ Hartree in the Hamiltonian) has been dropped."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {
+ "collapsed": true
+ },
+ "source": [
+ "## Drawbacks"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "* The Born-Oppenheimer approximation neglects nuclei, although this doesn't factor too strongly into the examples we have used.\n",
+ "\n",
+ "* The choice of a too small basis and/or one consisting of too simple functions (here GTOs) can be insufficient to describe the system accurately. Bigger sets (STO-6G) and/or more elaborate functions get computationally expensive quickly.\n",
+ "\n",
+ "* The wave function is approximated by a single Slater determinant. Each electron sees the average density of all other electrons (compare: mean field theory), which doesn't factor in electron correlation.\n",
+ "\n",
+ "The last point is addressed extensively in \"post-Hartree-Fock\" methods (e.g. using a sum of \"excited\" Slater determinants)."
]
},
{
--
GitLab