# Errors in the material model

**URL:** <https://community.geodynamics.org/t/errors-in-the-material-model/3764>\
**Category:** ASPECT\
**Created:** [November 29, 2024, 8:36am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764 "2024-11-29T08:36:41Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ddarkerlu](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/ddarkerlu/32/1866_2.png) [@ddarkerlu](https://community.geodynamics.org/u/ddarkerlu)\
**Post date:** [November 29, 2024, 8:36am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/1 "2024-11-29T08:36:42Z")

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Hello, everyone

Recently I was trying to talk about free surfaces in a spherical shell model, I made some changes to the parameter file, and encountered some confusion in the material model modification. I have declared the Reference density and given a specific value, but at run time I say that there is no entry named declared in the current section. May I ask where I made a mistake?

best

lu

 ![1911ace57e1cdfe9c1c76700a54b92b8](https://canada1.discourse-cdn.com/flex036/uploads/geodynamics/original/2X/d/d047f04e555ae6d6b6a6254619d1d82619d0490c.png)

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**Author:** ![ddarkerlu](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/ddarkerlu/32/1866_2.png) [@ddarkerlu](https://community.geodynamics.org/u/ddarkerlu)\
**Post date:** [November 29, 2024, 8:37am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/2 "2024-11-29T08:37:32Z")

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![88dd1819ef201b72644230bf94038553](https://canada1.discourse-cdn.com/flex036/uploads/geodynamics/original/2X/1/158cb93e76adbd137e67fb9007b88ac4f07b11f9.png)

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**Author:** ![bobmyhill](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/bobmyhill/32/38_2.png) [@bobmyhill](https://community.geodynamics.org/u/bobmyhill)\
**Post date:** [November 29, 2024, 9:12am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/3 "2024-11-29T09:12:58Z")

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Dear Lu,

Please post the whole input file and the whole error message.

We’d also prefer it if you simplified your input file to the simplest possible that still showed the error. This will help us debug, or in the best case scenario might reveal the source of the error to you.

Best wishes,  
Bob

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**Author:** ![bangerth](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/bangerth/32/52_2.png) [@bangerth](https://community.geodynamics.org/u/bangerth)\
**Post date:** [November 30, 2024, 12:59am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/4 "2024-11-30T00:59:09Z")

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@ddarkerlu Actually, I think the error message is quite clear: Apparently, in line 81 of your input file, you are referencing a parameter “Reference density”. But, in the section line 81 is in, no such parameter exists. If line 81 is in the part that you show, that would be in the “Material model/Visco Plastic” section. And it is true, if you look at [https://aspect.geodynamics.org/doc/parameter\_view/parameters.xml](https://aspect.geodynamics.org/doc/parameter_view/parameters.xml) and type “Visco Plastic” into the search box, that that section does not have such a parameter.

Best  
Wolfgang

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**Author:** ![ddarkerlu](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/ddarkerlu/32/1866_2.png) [@ddarkerlu](https://community.geodynamics.org/u/ddarkerlu)\
**Post date:** [December 5, 2024, 6:59am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/5 "2024-12-05T06:59:12Z")

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Dear Bob,  
Thank you very much for your reply. It seems that there is something wrong with my model parameter setting as Wolfgang said, but I have also encountered similar problems before. If I still encounter any difficulties in the future, I hope to get your help.

Best wishes,  
Lu

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**Author:** ![ddarkerlu](https://yyz2.discourse-cdn.com/flex036/user_avatar/community.geodynamics.org/ddarkerlu/32/1866_2.png) [@ddarkerlu](https://community.geodynamics.org/u/ddarkerlu)\
**Post date:** [December 5, 2024, 7:01am UTC](https://community.geodynamics.org/t/errors-in-the-material-model/3764/6 "2024-12-05T07:01:50Z")

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Dear Wolfgang,  
Yes, you are right, I have consulted the manual, this is a mistake I made, now the problem has been solved, I am still slowly trying to improve the parameter file, thanks for your reply.

Best wishes,  
Lu