Underlying physical basis of the gulp and the Claff force feild for simulating the properties of minerals

GULP
1

I want to know the the underlying physical basis of the gulp and the Claff force feild for simulating the properties of minerals under high pressure and temperature. Who can give me some advices? Thank you.
Lei LIU

2

Hi Lei Liu,

That’s a very open-ended question. The physical basis of GULP for all materials is described in the manual and in the references on the GULP home page (http://gulp.curtin.edu.au/gulp/). If you read this then you’ll have all the information you need for ClayFF and beyond.

Julian

3

Thank you very much for you reply. The situation what I meet now is that I calculated the density and sound velocity of a mineral under high pressure and temperature uesd the gulp with ClayFF. But the results are different with the experiment (The differences are about 5%-20.). And our calculated pressure gradient of density are always higher than the experimental result. So I want to find the reasons. One editor of

4

One editor of a journal also advice me to make a clear introduction on the basic theory of GULP because very few works are presented in the Earth science by GULP. Therefor, I want to find some advices and help from here.

5

GULP is actually used as much in mineralogy as other fields. The methods for calculating properties in GULP are fundamentally no different from any other lattice dynamics code, including those based on DFT etc. As with all interatomic potential codes, the quality of your results are largely determined by the quality of the force field that you feed in (assuming you have a sensible structural model)…

6

The ClayFF force field was used by us to simulate the density and sound velocity. I am sured that the uesed mienral structure is reasonable. Can i send my results to you and help me to find the reasons for our calculated differernce with that of experiments ?

7

For ordered crystalline materials the structure is not usually the problem. No need to send results - the problem will be that the force field you have input is not as accurate as experiment (which should be no surprise as theoretical models are rarely exactly quantitative). If you want better results you therefore need an improved force field…

8

Exactly! I think the clayFF force field that used in my work is a universal force field for most minerals. The best way for a special mineral, a specificl new force field shall be fitted or constructed on the base of existing force field, yes?

9

Dear Julian, I want to add some contents on the basic theory of GULP and ClayFF force field to my manuscript. Please give me some advices or published references. Thank you very much.

10

I think we’ve gone round in a circle!
Remember that Web of Science/Scopus etc are excellent tools for literature searching.
References support the arguments you want to make based on your knowledge of the literature and so only you know what you’ve read & understood.

11

Yeah. Thank you. It is my firt result by the gulp. More reading is the best way to solve this question. Thank you again. Lei