We develop the path integral method for quantum chemistry, apply the Monte Carlo method to an evaluation of the path integral, and calculate the ensemble average of the energy. For finite temperature, a simple Monte Carlo evaluation of the path integral brings out the negative-sign problem. In this
Path integral Monte Carlo method for ab initio calculation
β Scribed by H. Kawabe; H. Nagao; K. Nishikawa
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 550 KB
- Volume
- 60
- Category
- Article
- ISSN
- 0020-7608
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β¦ Synopsis
The Feynman path integral method is applied to the many-electron problem. We first give new closure relations in terms of ordinary complex and real numbers, which could be derived from an arbitrary complete set of state vectors. Then, in the path integral form, the partition function of the system and the ensemble average of energy are explicitly expressed in terms of these closure relations. It is impossible to evaluate, the path integral by direct numerical integrations because of its huge amount of integration variables. Therefore, we develop an algorithm by the Monte Carlo method with constraints corresponding to the normalization condition of states to calculate the required integral. Finally, the ensemble average of energy for the hydrogen molecule is explicitly evaluated by the quantum Monte Carlo method and results are compared with the result obtained by the ordinary full configuration interaction (CI) method.
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