How to find collaborators for a research project(paper or a series of papers)?

You can probably find colleagues easily. The challenge is interesting them in a collaboration with you.

The basic rule is that collaborations are successful when everyone benefits. In order to get collaborators, you need to make it clear that they will benefit by working with you on your idea. Benefit in academia usually takes the form of:

• Funding
• Publication authorship
• Advancing the collaborator's pre-existing research interest

You have already mentioned one potential benefit of your work: high-impact publications. The key is communicating (and convincing) colleagues that they will benefit.

Here are some things that might help:

• Have a concrete proposal. While some open-ended early discussions might be useful, once you are ready to invite people to collaborate, invite them to something specific. Do you want to write a paper together that demonstrates XYZ? is a clear idea that colleagues can quickly evaluate to decide whether they are interested. On the other hand, Should we work together in area X? is far too open-ended. It is not clear whether it will lead to anything useful, and busy academics will be reluctant to invest a lot of time in discussions that might not lead anywhere.*
• Demonstrate credibility. A colleague might be interested in your idea, but still reluctant to get involved if they don't know whether you are able to accomplish what you propose. The bigger and bolder your idea, the more skepticism you are likely to face from others. Some ways to demonstrate credibility:
  • Existing track record (publications, etc.)
  • An introduction from someone known who can vouch for you.
  • Networking and conversations that give people an insight into your knowledge.
• Offer to collaborate with others on their ideas. You ought to be the kind of colleague that you hope others will be for you. This means being willing to contribute to other projects. Offering to help others, besides being nice, also gives you a network and credibility for advancing your own ideas later. And in practice, advancing your own ideas often means compromising with someone else on a project that does some of what you both want.

*When I was trying to get collaborators on a grant application, I made the mistake of being too open-ended. It seemed like appropriate deference to others who were more experienced to approach them without a well-formed idea. However, these discussions didn't go anywhere. Eventually I realized that making a clear, concrete proposal was a service to everyone, as it gave them a much better idea of what I was talking about and whether it was worthwhile. "Let's apply for funding from this specific grant call, based on this short summary idea" got an immediate response from others. In the end, more experienced colleagues did shape the proposal quite a lot, but the specific proposal was a much better starting point for successful collaboration.

As a rule of thumb, if your approach even scared away internal ("friendly") collaborators, trying the same with external researchers that you do not have existing connections to seems like an exercise in futility.

This means that you first need to figure out what went wrong the first time you reached out to people at your university. Of course it is entirely impossible to debug your approach to find collaborators over the Internet and based on 5 lines of text, but I have a few educated guesses:

• Maybe you can work on your clarity of expression. Based on this and other questions you have put to Stack Exchange you seem to compress quite a lot of information and assumptions into a few meagre lines of very tense text. Without having actually seen a research proposal by you, I assume that it may come across rather convoluted.
• You seem inexperienced as a researcher. I say this because the only people I have ever heard talking about a string of papers in leading journals (with a specific IF, no less) even before any actual work has been conducted to be researchers with little experience in publishing at high-impact venues. While being inexperienced is no problem per se, people obviously tend to regard the research proposals of juniors with a little more scepticism.
• Have you considered what is "in it" for your collaborators? What qualities do you have that they don't (note that "a lot of time" can be a solid answer)? How will this project fit in with their current work and interests? How and what can they contribute? Always keep in mind that "I need skill A and you are an expert in A" is a terrible reasoning from the other side of the table.
• Are the roles in the collaboration clearly defined, and have you made those roles explicit? Are you looking for a mentor? People that help you with specific scientific / methodological aspects? Programmers or wet lab staff? Again, consider what is in it for them - if you are looking, for instance, for a mentor, why would this person supervise you, and not spend the same time on her or his own students?

The best place to begin to look for collaborators are researchers who are currently publishing in your topic/field of interest. I would recommend contacting the authors of journal articles you read and can contribute to the topic in a significant manner (enough to be published). Contact the researcher and suggest a collaboration, with what skills and expertise you bring to the table and your intended result of collaboration.