Support

Support for vampire is available from various sources. The first port of call should be the pdf manual, which details the basics of setting up the code and includes a reference for the available options. If a manual is unable to answer your question, then please look at the FAQs below and previous topics on the mailing list to see if a similar question has been asked before. Failing that, please post a new query to the mailing list which will reach the developers who may be able to help.

Manual

The manual for vampire is currently under development, and is expected to improve significantly over the course of 2014 as time allows. The latest version of the pdf manual is available to download here, which covers the essentials of installing or compiling the code on different platforms, setting up simulations, running the code, and a comprehensive command reference. User contributions and improvements to the manual are particularly welcome.

Vampire manual PDF 4.0 (500 kB download)

Mailing list

The vampire-users mailing list is an excellent way to ask questions about all aspects of vampire, and we would encourage all users to sign up. Questions about the code, setting up simulations or the aomistic model are all welcome. All bug reports and feature requests should also be made through the mailing list.

groups.google.com/forum/#!forum/vampire-users

FAQ

Any FAQs from the mailing list will be added here for quick reference.

Which papers should I cite if I publish results using vampire?

Maintaining and developing the vampire code is a time consuming process, and in order to obtain continued funding it is most helpful if its usefulness to the magnetism community is demonstratable in terms of citations. If you use the vampire code in your research please cite the following methods paper:

Atomistic spin model simulations of magnetic nanomaterials
R. F. L. Evans, W. J. Fan, P. Chureemart, T. A. Ostler, M. O. A. Ellis and R. W. Chantrell
J. Phys.: Condens. Matter 26, 103202 (2014)

In addition to the general reference, additional features of the code are detailed in some additional references which may be appropriate if you make use of them. If you use the constrained Monte Carlo method for constrained energy minimization please cite:

Constrained Monte Carlo method and calculation of the temperature dependence of magnetic anisotropy
P. Asselin, R. F. L. Evans, J. Barker, R. W. Chantrell, R. Yanes, O. Chubykalo-Fesenko, D. Hinzke, and U. Nowak
Phys. Rev. B 82, 054415 (2010)

If you use the temperature rescaling method please cite:

Quantitative simulation of temperature-dependent magnetization dynamics and equilibrium properties of elemental ferromagnets
R. F. L. Evans, U. Atxitia, and R. W. Chantrell
Phys. Rev. B 91, 144425 (2015)

Can I use vampire for my academic/personal/commerical project?

Yes - vampire is free to use for all research projects. The only restrictions are that any modifications or additions to the code are also (eventually) made open source, as per the terms of the GPL licence.

There are numerous definitions of the exchange in the literature. How do I calculate the exchange constant for vampire?

In vampire the exchange interaction is defined as

H = -∑ij Jij SiSj

In the literature there is often an additional factor 1/2 accounting for the double summation ij and ji. In the code both interactions are calculated explicitly, and so the above definition of the exchange interaction is used. For example, if one takes a hydrogen molecule with 2 spins we have

Eex = - Jij SiSj - Jji SjSi = -2 Jij SiSj

Using ab-initio methods it is often possible to calculate the total energy of the system depending on the orientation of the spins. Taking the two spin system as an example and considering the FM state then Eex = -2 Jij and for the AFM state Eex = +2 Jij. The total energy difference is therefore

ΔE = 2 Jij - 2 Jij = 4 Jij

Therefore, to extract the exchange energy from the total energy for the two spin system we have

Jij = ΔE/4.

Vampire development

Vampire is an ongoing project, and there are many features we wish to implement but so far have not had the time to do. New feature requests will appear here along with their expected implementation date. If there are features requests please post a message on the mailing list, and we will consider how it might be implemented. We also welcome contributions from other researchers. A code development guide is in the works, but in the meantime if you wish to contribute some code or functions please get in touch so that we can give some guidence regarding integrating the new features in a sustainable way.