worms's Introduction

worms: a simple worm code

This is a sample code describing how the non-reversible worm algorithm (a.k.a directed-loop algorithm) can be implemented in the continuous imaginary time path integral representation. It calculates an S=1/2 antiferromagnetic Heisenberg chain in a longitudinal magnetic field.

Prerequisites

CMake - http://www.cmake.org

Compilation

mkdir worms-build
cd worms-build
cmake [path-to-worms-source-directory]
make
make test

Command line options

Please see the output of

./worms -h

Release Note

Release 1.0 (2013/09/12)
- Initial version
Release 1.1 (2014/02/24)
- Fixed generation of transition matrix under the magnetic field
- Updated logic to optimize number of worms per MCS
- Added energy measurement
- Added timer
- Updated documents
- Added check scripts and tests

References

O.F. Syljuasen and A.W. Sandvik, "Quantum Monte Carlo with directed loops," Phys. Rev. E 66, 046701 (2002).
N. Kawashima and K. Harada, "Recent Developments of World-Line Monte Carlo Methods," J. Phys. Soc. Jpn. 73, 1379 (2003).
H. Suwa and S. Todo, "Markov Chain Monte Carlo Method without Detailed Balance," Physical Review Letters 105, 120603 (2010).
S. Todo, "Loop Algorithm" in Strongly Correlated Systems: Numerical Methods (Springer Series in Solid-State Sciences), ed. A. Avella and F. Mancini (Springer-Verlag, Berlin, 2013), p. 153.

Developers

Synge Todo (University of Tokyo)

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worms's Issues

./worms -L 4 -T 0.25 -H 0.5 がクラッシュする

行列要素の作成ルーチンがおかしい

多体相互作用への拡張

./worms -L 4 -T 0.25 -H 0.5 がクラッシュする

行列要素の作成ルーチンがおかしい

多状態模型への拡張

Test failed (version 1.0)

出力ファイルとテストファイルとでバージョン番号があっていないのでテストに失敗します。
手で直したほうが速い気もしますが、パッチファイル添付しておきます。

diff --git worms.op worms.op
index 5f89c71..c0818fc 100644
--- worms.op
+++ worms.op
@@ -1,4 +1,4 @@
-worms: a simple worm code (release )
+worms: a simple worm code (release 1.0)
Copyright (C) 2013 by Synge Todo [email protected]
https://github.com/wistaria/worms

磁場入りの場合の結果がおかしい

./worms -L 4 -T 0.25 -H 0.0 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.1 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.2 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.3 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.4 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.5 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.6 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.7 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.8 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 0.9 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.0 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.1 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.2 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.3 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.4 | grep 'Uniform Magnetization '
./worms -L 4 -T 0.25 -H 1.5 | grep 'Uniform Magnetization '