It's very simple. Join my library (collection of models) and you will have access to many thyristors, triacs and diacs. And many other models. There is also my advanced diac model, DB3. This is a parametric model and it can be adjusted for other diacs.
It's a link to my website: http://bordodynov.ltwiki.org/
Thank you very much Borododynov for the support. I am new user of LTSpice and also new member. I will go through it and if any query, can I contact you through mail? My mail ID is [SNIP]. Please send your mail ID if possible, otherwise through the group, surely I will get the support from you. Thanks and regards.